I have a new H-P (HPQ) laptop and there are several preinstalled media-playing interfaces that have been foisted on me. Do I really need all of these interfaces? Can’t I just get all of this media to run through Windows Media Player or iTunes?

Since you weren’t specific, I don’t know what media software came with your new laptop. I’m sure some of it may have been redundant “craplets” — the unwanted software PC makers load onto their machines in order to collect a fee from the programs’ publishers. And you are correct that many of the most common audio and video file types can be handled by Windows (MSFT) Media Player and iTunes.

However, the Internet is full of media file types that are best played, or can only be played, in specialized software — either separate applications on your computer or online players that are enabled via your Web browser. So, over time, most users will collect additional players, or plug-ins for their Web browsers, that will supplement their main media-playing program. One way to see if the media software on your new computer is necessary is to test what types of files it handles. If you can open and play these same files in Windows Media Player or iTunes, and you prefer to do so, then you probably don’t need the added software.

If I am running Windows Vista on my iMac desktop using Parallels, will Apple’s Time Machine backup program automatically preserve the Windows hard disk, too?

Yes. Parallels, and its competitor, VMWare Fusion, create virtual Windows hard disks inside a Macintosh. When you are running Parallels or Fusion, Windows sees these virtual hard drives as if they are distinct physical disks. However, they are in fact just very large files on your Mac’s hard disk. So Apple’s (AAPL) Time Machine backup program treats them like any other file and backs them up. Time Machine can also restore these virtual Windows hard disks, in their entirety, just as it can restore other kinds of files.

There are some caveats, however. Time Machine treats each virtual Windows hard disk as a big, unified blob of data, so it cannot peer inside them to recover individual Windows files you may have accidentally deleted while running Windows programs. Also, if your virtual Windows hard disk is large, and it changes often, then using Time Machine to back it up may suck up a lot of space on your backup drive, as numerous archived versions of the file accumulate.

I currently have a DVD player and a large stack of DVDs that I play through my analog TV set. After the 2009 digital TV conversion, will I still be able to use my existing DVD player and play my existing DVDs, even if I buy one of the government-subsidized converter boxes?

The FCC says DVD players and other add-on gear “will continue to work, even if they are only analog-capable.” But it adds that “manufacturers are producing a number of different connectors to hook equipment together and improve picture and sound quality. Check with your equipment retailer to determine the types of connectors that will work with your equipment.”

In other words, while there’s no inherent conflict, it all depends on your particular DVD player, your particular TV set, and how you have them connected. The best thing to do is consult closely with the dealer or manufacturer selling the converter box so that you understand how it can coexist with your current DVD player setup, or how you might have to alter your current setup.

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

My Dell PC, which is an older model running Windows XP, is very slow to boot up and I have a lot of icons on my desktop. Does the number of icons on my desktop have any relationship to the time it takes my PC to boot up?

Everything a PC must do when it starts up takes some time, and that includes drawing the desktop. A desktop with fewer icons takes less time to re-create. But, if your machine is “very slow” to start up, you may also have accumulated too many programs that are set to run upon start-up, including programs that you can’t see because they are launching behind the scenes. So, it would be wise to examine these programs and remove or disable as many as you can, keeping only those you really need. I suggest you obtain and run a program designed to help you do this. One good one comes from PC Magazine and is called Startup Cop Pro 3. It costs $8 and can be found at pcmag.com/downloads.

If I buy a Mac, can I move all the programs on my Dell over to the Mac?

While most common Windows file types can be copied to a Mac and will work there, the Windows programs on your Dell won’t run on the Mac’s operating system, so there’s no point in moving them to a Mac. There is one exception: If you plan to install and use Windows on your Mac, then your programs should run. However, some programs are designed to be locked to a single PC and won’t run on a second machine, even if it is a new Dell instead of a Mac running Windows. Furthermore, it can be difficult to move Windows programs to a new machine, because they are often made up of parts that are scattered in various places on the hard disk.

Two of the companies whose software allows you to run Windows on a Mac, Parallels and VMWare, do offer utilities that will copy the contents of a Windows PC to the portion of the Mac devoted to running Windows. The Parallels utility is called Transporter and the VMWare utility is called Converter.

Like many Internet users I have used Wi-Fi in airports, hotels and coffee bars. I have used it to access banking and brokerage accounts. Just how much at risk have I been? I am a Mac user. Am I more or less at risk than a Windows user?

No matter what kind of computer you use, there is some chance, however small, that a crook can intercept any data you send or receive over a public wireless network. So, my advice is to never, ever conduct financial transactions, or any highly sensitive communications, over any network you don’t control. It’s the same principle people should use when making voice calls on cellphones, which are easier to intercept than voice calls made on land lines. Be cognizant of the content of your communications of any kind when you are using public wireless networks.

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

I have a Dell Dimension that is six or seven years old. Recently, the following message appears every time we start the computer: “WARNING: Dell’s monitoring system has detected that Drive 0 on the primary EIDE controller is operating outside of normal specifications. It is advisable to immediately back-up your data and replace your hard disk drive.” When we hit F1, the computer boots normally and functions fine. All our data is backed up on an external drive. What is going on? Is it time to bite the bullet and get a new computer?

I don’t know exactly what’s going on, but you should take the warning very seriously. It’s good that your data is backed up, but if your hard disk fails, you won’t be able to use the computer. Six or seven years is a long time to keep a computer, and hard disks do go bad. Just because it continues to work doesn’t mean it isn’t on the verge of sudden failure. At the very least, have Dell or a local technician diagnose the hard disk to see if it is a serious problem or one that can be easily fixed. If the disk is failing and you are otherwise perfectly satisfied with the computer, you can get a new drive that is much larger for a reasonable sum. You should also seriously consider buying a new computer, simply because everything else on your machine is also out of date and, as time goes on, you may find that more and more software and Web sites won’t work well with it.

Does either Parallels Desktop or VMWare Fusion support multiple virtual machines installed on a Macintosh — for instance, one running Windows XP and one running Windows Vista?

Yes. Both of them allow you to create multiple virtual computers, running Windows XP or Vista, older versions of Windows, or Linux, as long as your Mac has sufficient hard-disk space.

My Toshiba Satellite runs Windows XP Home, and it takes more than four minutes when starting up before I can open any programs. Is my computer running too many programs at start-up? If so, how can I view them and shut down the unnecessary ones?

That certainly could be one cause of the problem. It’s a common situation. To see what programs are set to run when you start up your computer and to turn off unwanted ones, you can use a somewhat geeky built-in program from Microsoft or simpler ones available from outside software vendors. To run the built-in program, go to the Start Menu, click “Run,” and in the blank box that appears, type in “msconfig.” This utility will let you turn on and off invisible start-up programs. Go to the tab marked “Startup” and check off any you don’t want. But be conservative — don’t turn off anything you don’t recognize and know is unneeded. A better solution, easier to use and with more information, is an $8 utility from PC Magazine called Startup Cop Pro. You can get it at: www.pcmag.com/article2/0,1759,2177188,00.asp. There are a number of similar programs that may work just as well, but unlike Startup Cop, I haven’t tested them and so can’t recommend them.

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

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