I need some help sending videos to others. It seems that every video I try to send in various ways is always too large. I’ve tried to use a program that works with Outlook to compress the email attachment, but it’s always still too large. Is there a solution other than uploading them onto YouTube or something similar?

I suggest you try one of the services that specifically exist to transmit files that are too large for email. They typically work by having you upload the files to their servers, which, unlike YouTube, don’t expose them to the world. Seconds after you upload these files, your recipients receive an email that includes a specific link to the file you uploaded. The email is small because it includes only the link, not the file itself. The recipient clicks on the link, and the file is downloaded to his or her computer.

The service I use for this is called YouSendIt, and can be accessed at yousendit.com. It works in all the major Web browsers, and on both Windows and Macintosh computers. The company has a free plan that covers files of up to 100 megabytes in size, and allows each file to be downloaded up to 100 times, or up to a gigabyte of total downloads each month. For $10 a month, you get a maximum file size of two gigabytes, 500 downloads per file, and a monthly maximum limit of 40 gigabytes.

In my experience, YouSendIt works well. It can be used directly from within a browser, or via a small program called YouSendIt Express, that lives on your computer and handles large files faster than the browser version does. YouSendIt also offers an Outlook plug-in that can automatically route large downloads via the service rather than through regular email, though I haven’t tested this plug-in.

Our daughter is heading off to college this fall. She will be an art/graphic-design major, and the school recommended that she buy an Apple MacBook. I’m not sure if she should get what the college calls the “midlevel MacBook” or the “advanced MacBook.” The only differences are a slightly faster processor, a hard disk that is 40 gigabytes larger, and a “SuperDrive” for CDs and DVDs rather than a “Combo” drive. The price difference is $90. Which should we buy?

Either machine would be fine, and a lot depends on your budget, since college itself is of course very expensive. But I think, in this case, the extra $90 would be worth paying. This has nothing to do with the processor speed, which she probably wouldn’t even notice. But, if she is going to be creating a lot of graphics files, which can be large, the extra hard-disk space could be important.

The same goes for the CD/DVD drive options. The “SuperDrive” is Apple’s term for a drive that can create both DVDs and CDs, while the “Combo” drive can create only CDs. (Both drives can play both types of disks.) For someone who is producing large files, the ability to create DVDs can be handy, since DVDs have much higher capacities than CDs.

My laptop has been infected by rogue viruses, posing as antispyware programs, that I can’t get rid of. When I go on Google, I find a number of sites that claim to offer free software that will get rid of them, but I am reluctant to download anything onto my machine from a source that I am not sure of. What’s a reliable program that will do that job?

I would immediately buy a genuine, legitimate commercial antispyware program, install it and run it. The best ones I know of are Spyware Doctor by PC Tools, at pctools.com, and Spy Sweeper from Webroot, at Webroot.com. Each costs $30, but that price can save you a lot of heartache.

You can find Mossberg’s Mailbox, and my other columns, online, free, at the new All Things Digital Web site, http://walt.allthingsd.com.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about antispyware software, Powerline adapters and the Mac mouse button.

I set my parents up with a new Dell PC, and included antispyware software that I run periodically to clean up the computer. I recently discovered they had more than 200 instances of spyware on the machine. This may be because my 81-year-old father surfs porn sites ALL the time (this isn’t a joke). Is there any way to keep his computer bulletproof and safe?

Assuming you can’t dissuade him from the porn sites, which are common sources of spyware and adware, your best option is to switch to a type of antispyware program that blocks the installation and operation of spyware and adware programs as it is happening, rather than waiting until they are installed to clear them out. The best program I have tested of this type is Spy Sweeper from Webroot, but there are others. These types of programs usually aren’t free, but their prices are modest and they would allow your dad to spend his golden years as he sees fit.

Last week, you recommended Powerline adapters that can route an Internet connection over the regular electrical wires in your house. I have two questions about these products. If a home has two different circuit-breaker boxes, can adapters plugged into outlets connected to the different boxes communicate? And, could a neighbor who shares an outside electrical line potentially spy on my Internet usage?

I am not an expert on electrical systems, and neither of these circumstances applied to my tests. So I asked Netgear, the manufacturer of the XE104 adapters I reviewed last week.

The company says that if the two adapters are plugged into outlets that are on totally independent electrical “loops,” they won’t be able to communicate, because the electrical current itself wouldn’t pass between the loops. However, Netgear claims it is “extremely rare” for a home built after 1950 to have two wholly independent loops, even if they have two different circuit-breaker boxes. The company says that, at least in newer homes, separate circuit boxes are often linked.

However, I would add that electrical layouts vary so much that there is no guarantee that any two electrical outlets will have a connection that will work with Powerline adapters. I believe it will work in the vast majority of cases, but not all. In my home, which is 36 years old, the adapters did work between rooms with different circuit-breaker boxes.

On the security issue, the company says it is theoretically possible, but very unlikely, for a neighbor on your same outside electrical line to spy on a network running over your interior electrical wires. To do so, Netgear says, the neighbor’s house and yours would have to lack a filter between them, and those are commonly present. Even then, a nosy neighbor would have to know that you have a Powerline network — and buy a compatible adapter — in order to access your network.

This is likelier, but still not very probable, in an apartment building, because circuits in such buildings are often shared. The company does include optional encryption software for such situations, so that even if a neighbor can snoop on you, he wouldn’t be able to decipher your network traffic.

I am thinking of buying an Apple MacBook, but I notice it only has one button below the touch pad, and no obvious scrolling control. Without buying and using a mouse, how can you right-click and scroll on a Mac laptop?

The Mac operating system and Apple software do in fact support right-clicking, displaying the same sort of pop-up menus that Windows does. However, on a Mac laptop with the single button, the traditional method for right-clicking has been a clumsy one: holding the Control key while clicking the button.

Now, the latest Mac laptops have a much easier and cleverer method for right-clicking: you just place two fingers on the track pad and click the button. It’s fast and easy, though still not as good as if Apple abandoned its odd mouse dogma and simply built dual buttons into its laptops.

Also, the new Mac laptops have a method for scrolling that I find superior to the methods common on Windows laptops: you just place two fingers on the touch pad and drag them up or down together. It quickly becomes second nature.

* * *

Because of the volume of email I receive, I can’t routinely answer individual questions by email, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

Write to Walter S. Mossberg at mossberg@wsj.com

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about moving iTunes files to a new computer, file-compressing programs and security software.

If you have a question, send it to me at mossberg@wsj.com, and I may select it to be answered here in Mossberg’s Mailbox.

I recently bought an Apple iBook to replace an old Dell laptop. How do I move my iTunes music files from the Dell to the Apple?

Your iTunes music files work on both Windows and Mac machines, as does the special iTunes Library file that keeps track of play lists and the like. So, all you have to do is copy these files from the Dell to the Apple, as with any other files you want to move. In fact, even if you were moving from an old Dell to a new Dell, without changing operating systems, the process would be the same.

If you have allowed iTunes to gather all of your files into the folder called “iTunes” within “My Music,” all you have to do is copy that folder to the iBook. This can be done in a number of ways, but the best choices would be to do this via a home network or by burning the files to CDs or DVDs and then copying them from the CDs or DVDs onto the Mac. On the Mac, the iTunes folder is usually located within the Music folder.

If your music files are scattered, or are in the My Music folder, but not the iTunes folder, you’ll have to locate them before copying them. Be sure to copy the iTunes folder also, because it contains the iTunes Library file.

If you have an iPod and it contains all of your songs and play lists, you can skip these steps. Just download one of the many cheap utility programs for the Mac that will copy the contents of an iPod to a computer. Two examples are PodWorks and PodUtil, the latter of which comes in a Windows version for Windows-to-Windows transfers.

One more thing: Be sure to deauthorize the Dell from your iTunes account before authorizing the Mac, so you don’t waste one of your maximum of five slots for computers that can play any songs you purchase. To do this, fire up iTunes on the Dell, go to the Advanced menu and select “Deauthorize Computer.”

What program do you recommend the most for compression and decompression of files? Winrar, WinZip or any other program?

On Windows, I use WinZip (www.winzip.com), because of its flexibility, even though the operating system can compress and decompress files by itself. On the Mac, I use Stuffit (www.stuffit.com), for similar reasons. A decompress-only version of Stuffit came with earlier versions of Mac OS X, Apple’s operating system. The current version of OS X, Tiger, can compress and decompress files in the popular Zip compression format without Stuffit.

I run Norton Internet Security, Ad-Aware and Spybot on my computer to keep “bad stuff” from infecting my system. Yet last week a malicious program attacked my computer. It hijacked my wallpaper and put a huge warning on my desktop. My security software never knew it was there. Do I need to run additional security on my computer?

This category of spyware or adware is expanding so fast that, even with the two good anti-spyware programs you are using, attacks can happen. My only advice is to add a third, such as Webroot’s Spy Sweeper, which is my favorite. I know this is annoying, but until the spyware/adware epidemic slows down, it is often necessary for Windows users to have multiple defenses.

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about switching between software provided by camera companies, Web-based tax-preparation software and scheduling antispyware sweeps.

If you have a question, send it to me at mossberg@wsj.com, and I may select it to be answered here in Mossberg’s Mailbox.

I have been using Olympus digital cameras for years, so I have a library of Olympus digital photos using Olympus software. If I were to switch to a Canon camera, how easy is it to also switch software? Is there an easy way to transfer the Olympus photos into the Canon software?

Unless you are doing something unusual, all your photos from both cameras should be in the standard format called “jpg” and I assume either company’s software can handle all of them. However, I don’t recommend using the software supplied by camera makers. They may be fine at making cameras, but, with the exception of Kodak, they usually create lousy software. Instead, I suggest getting a good, general photo-organizing program, and making that the center for managing your pictures — whatever camera you use.

Every Macintosh computer comes with a superb program called iPhoto for organizing, sharing and editing photos. Windows computers don’t come with anything as good, but you can download a free program called Picasa from Google, at picasa.com. Or, you can download Kodak’s very nice EasyShare software, at Kodak.com. It’s free, comes in versions for both Windows and Mac, and doesn’t require a Kodak camera or printer to use. Paid software that also does the trick on Windows includes ACDSee, at acdsystems.com; and Corel Photo Album, at corel.com.

In 2002, you advised against using Web-based tax-preparation software, writing, “Your tax data are highly sensitive and confidential, and I think the Web is just too susceptible to hackers and crooks to make it a fitting repository for such information.” Do you continue to have these concerns?

Yes. If anything, the incidence of identity theft and other security problems on the Web have grown worse since 2002. I am not criticizing the tax-preparation companies, which I assume have good security. And I am not advising people against normal e-commerce, or the use of credit cards online. But I would be personally loath to put the broad and deep financial information required for a tax filing on a server controlled by someone else and connected to the Internet. I would instead download or buy traditional tax-preparation software, which keeps your data on your own hard disk.

I have the Spy Sweeper antispyware software that you recommend, and am wondering how often you suggest scheduling it to automatically scan my computer for software. I was thinking once a month.

Once a month isn’t good enough if you are an active Internet user, or your computer is on a broadband connection and stays on, and connected, all the time. I run both spyware and virus scans nightly on my Windows computers, and I advise all Windows broadband users to do so. There’s no downside, if your computer is on all the time anyway. I also advise setting the software to run in the background, guarding your PC against new intrusions.

Write to Walter S. Mossberg at mossberg@wsj.com

Here are a few questions about computers I’ve received recently from people like you, and my answers. I have edited and restated the questions a bit, for readability. This week my mailbox contained questions about books for switching from Windows PCs to Macintosh, antispyware program and transferring files from an old computer to a new one.

If you have a question, send it to me at mossberg@wsj.com, and I may select it to be answered here in Mossberg’s Mailbox.

I am about to switch to the Macintosh after many years using only Windows PCs. Is there a good book to help me with the transition?

In addition to the many books about how to use a Mac in general, there are two that were written specifically to guide Windows users in making the switch to the Mac’s OS X operating system — though in my experience most Windows users can successfully switch without a book.

One book, called “Switching to the Mac,” is by David Pogue. The second, called “Mac OS X for Windows Users: A Switchers’ Guide,” is by David Coursey. Both authors are veteran technology writers. Neither book takes into account the latest Mac operating system, called Tiger, because they were published before Tiger appeared. But either should still be a strong guide to making the switch. The Pogue book is also slated to be updated next month with a new edition that covers Tiger. Mr. Coursey has also just published “The Mac Mini Guidebook,” which, while focused on Apple’s newest low-end model, has a lot of content on switching and covers Tiger as well.

In addition, there is a wealth of material on Apple’s Web site on how to switch from Windows. An entire section of the site, devoted to switching, can be found at www.apple.com/switch. A basic tutorial on the Mac can be found at www.apple.com/support/mac101.

About a week after I downloaded and installed the Google Toolbar, I noticed a strange looking program had knocked it off to the far right of my screen. I’m sure I unknowingly downloaded this piece of spyware and now it takes over my Google searches. Any suggestions on how to excise it?

You need to obtain and run a good antispyware program, and then keep it running all the time. In fact, at first, you may need to run several of them to expunge this particular piece of malicious software and any others you might have accumulated. My current recommendation in this category is Webroot’s Spy Sweeper, but there are other good ones, including Spybot Search and Destroy, Ad-Aware and CounterSpy.

I have an old Dell computer that I acquired in 1998. I would like to purchase the new eMachines PC recommended in your recent article. My problem is that I would have to transfer my files onto the new computer but my Dell only has a floppy drive and a Zip drive, and the eMachines PC lacks these drives. How can I do this?

You can connect the two computers with a cable and automatically transfer your files using software programs specially designed for this task, such as IntelliMover by Detto (www.detto.com) and Alohabob PC Relocator by Eisenworld (www.alohabob.com). These products usually include cables, but you may have to pay extra for a different cable that works with your old PC.

Another option would be to buy an external USB version of the Zip Drive, install it on the new PC, and then transfer your files via Zip disk. Such an external Zip drive can be bought starting at well under $100. See www.iomega.com.

* * *

Because of the volume of e-mail I receive, I can’t routinely answer individual questions by e-mail, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

Write to Walter S. Mossberg at mossberg@wsj.com

If you have a question, send it to me at mossberg@wsj.com, and I may select it to be answered here in Mossberg’s Mailbox.

Recently, my laptop is taking an inordinate time to boot up. I have tried disk cleanup, defragmentation, and multiple scans by antivirus programs but nothing seems to speed up the full bootup process. Do you have any suggestions?

This probably indicates that you have a large number of programs, many of them invisible to you, that are configured to launch at startup. Some may even be spyware and adware programs. I suggest two steps. First, get a good antispyware program, like Webroot’s Spy Sweeper, and do a thorough scan of your system, deleting all the spyware and adware you can find. Spy Sweeper, which costs $30, is available at www.webroot.com. (A free trial is available.) Then, reboot.

If the system continues to reboot slowly, you should run a program that tells you which programs are trying to launch at startup. Get rid of those you don’t need. A built-in Microsoft utility, msconfig, can do this for you. Just select Run from the start menu and type “msconfig.” Look over the programs listed in the “Startup” tab of the program, and uncheck all that you’re sure you don’t need. This may be tough, because msconfig doesn’t give the English names of the programs or explain what they do.

Even better, download and run a startup utility like Startup Cop, which explains things better. It costs $5.97 and is available at www.pcmag.com/article2/0,4149,2173,00.asp.

We would like to use the Internet wirelessly in our home, but we have a dial-up service. We were told by others that one has to have a cable or DSL modem to go wireless. Is that true?

No, you can do it with dial-up, though the speed is so slow that the experience over wireless may be disappointing. A company called Always On Wireless makes a wireless base station called the WiFlyer that is specifically designed for sharing dial-up connections wirelessly. It costs $150 and is available at www.wiflyer.com. I have seen it demonstrated, and it worked, but I haven’t tested it.

I run Windows XP home edition and also Word. After installing a newer edition of Word, I began to have a problem when I went to look for my newly prepared files. They don’t show up in the folder that I thought I put them in. How can I resolve this aggravating problem?

In Word, go to the Tools menu, and select Options. Go to the File Locations tab, and click on Documents. Set the location for saving documents to whatever folder you prefer, and click OK or Close until you are out of the Options window. That should take care of it.

* * *

Because of the volume of e-mail I receive, I can’t routinely answer individual questions by e-mail, or consult on individual problems or purchasing decisions. I read all questions I receive and select three each week to answer in the column.

Write to Walter S. Mossberg at mossberg@wsj.com