My computer takes forever to start up. I am tempted to just put it into hibernation or standby when I am done with it for the day, so that starting up will be quicker. Would I be damaging my computer by doing so?

Doing this shouldn’t cause any damage to your computer. For many users, one of these two techniques is standard procedure, in fact. Standby, or sleep, mode, gets you back to work more quickly, because the machine never completely shuts down. Its biggest downside is that, on occasion, computers fail to “awaken” properly from this mode, and you have to do a full restart. So I would advise that you carefully save any work before initiating standby.

In my experience, this kind of glitch is less likely to happen when you use hibernation, in which the computer does completely shut down, but first saves to the hard disk a record of the state of the machine.

When the computer restarts, all open programs and files are restored just as you left them. The downside here is that getting going again using hibernation takes longer than it does using standby mode. And, even though it’s more reliable than standby mode, I’d still advise saving all your work each time before using hibernation.

I am thinking about switching to a MacBook Pro laptop. I understand that it has a real good automatic Wi-Fi detection system. But if I also use a cellular modem card from Verizon or Sprint to access the Internet, won’t the two conflict?

No. The Mac operating system treats the two kinds of connections separately, each with its own user interface. It can detect and connect either one, if you have coverage of both types.

I’m interested in getting a laptop with LED display and SSD drive. Do you think the price for those components will fall drastically in three months’ time?

Displays that use light-emitting diodes (LEDs) have been around for a while and don’t tend to be a major deal breaker in the higher-end laptops in which they are commonly offered. But solid-state drives (SSDs), which replace hard disks with memory chips to store your data, are much rarer and newer and still can add significantly to the price of even a high-end laptop. I am no expert in price forecasting, but, while SSD prices will fall, I doubt they will drop “drastically” in as little as three months.

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.

I currently spend about $50 to $60 per year for Norton Security software. Is this necessary when Windows XP has its own security built into the operating system?

Windows XP doesn’t include antivirus or antispyware programs, so you definitely need some sort of add-on security software. If you don’t want to pay for it, there are free alternatives available.

How do we determine when to purchase a new PC? Our current Dell is about five years old. I’m feeling a little worried because I have my music and photos on the computer and don’t want to lose them.

There’s no universal answer to your question. In general, I don’t believe people should replace computers that are working well for them just because they reach a certain age. On the other hand, five years is pretty old for a PC. At that age, the odds increase that the hard disk may develop problems, and that newer versions of the software you like will require hardware upgrades that may cost more than you want to invest in an older machine.

Assuming your Dell is working fine, that you aren’t a power user, and that your music and photo activities are simple and basic, there’s probably no urgent need to replace the PC. But, to assuage your concern about “losing” your pictures and music, you might back up those precious files to an external hard disk or an online backup service.

Last week, you compared the start-up time of Windows Vista to Apple’s new Leopard operating system, and found Vista to be much slower. But you used different laptops for each. What would the numbers be on the same Macintosh running the two operating systems?

I ran the tests again on a single computer, a fairly new Apple iMac, which can be started up, and restarted, in either Vista or Leopard. I used the Mac’s Boot Camp feature, in which only one operating system is running at a time, has its own dedicated portion of the hard disk and fully controls the hardware. The machine uses an Intel processor and other key components commonly found on Windows machines, and runs Windows just like a Dell or any standard Windows PC, without any involvement from the Mac operating system.

This Vista installation doesn’t include any of the speed-robbing trial software commonly included by PC makers, though it does have security software from Symantec. However, the test results were very similar — Leopard started and restarted much more quickly than Vista did.

In this simple test, I timed both operating systems from a cold start and a restart until the computer was fully ready for operation, with the hard disk quiet and the network connection established. The cold start, beginning with the computer completely off, took Leopard 46 seconds, but took Vista one minute and 42 seconds. A restart, beginning with the computer running an email program, the Firefox Web browser, and Microsoft Word, took one minute and two seconds for Leopard, and three minutes and 17 seconds for Vista.

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

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

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 Windows Vista complaints, using antivirus software when running Windows on a Mac, and transferring large files.

In various past columns, you have complained that Windows Vista boots slowly and that it is incompatible with some software and hardware. Is this situation improving?

Microsoft claims that neither complaint affects most users, and that the minority of cases where they do is being whittled down steadily. I expect that the incompatibility issues, at least, will diminish over time. But I am still receiving reader complaints about incompatibility, so I have to assume that this issue remains real, at least for some people. The slow start-up issue will be harder to cure, as it involves factors like add-on trial software, called craplets, that are beyond Microsoft’s control. Officials at a number of Windows PC makers tell me they are beginning to get the message that people hate craplets. But I am still observing slow boot times in new Vista PCs I test and still see plenty of craplets.

If I run Windows on a Mac, do I need two copies of antivirus software, one to run in the Windows environment, and one to run in the Mac operating system?

You need only one copy, to run in the Windows environment. Macs have essentially no virus problem, and thus don’t need antivirus software. However, some Mac users install it to be extra safe, or to kill viruses that they fear might be passed on via email or over networks to people using Windows.

In last week’s Mailbox, you advised someone that he could copy a 25-gigabyte file from a Mac to a Windows PC using an external hard disk formatted for the Windows FAT file system. But I believe that won’t work. Do you have another solution?

You are correct that I erred. I forgot that the FAT file system, the only Windows format to which Macs can save files, is limited to file sizes of up to 4 gigabytes. This is almost never a problem, except in the case of extraordinarily large files. I did offer several alternate solutions last week, including using a network or cable transfer. But here’s another: You can use a Mac-formatted external hard disk, or a Mac-formatted iPod acting as a hard disk, to transfer the file, provided you have installed on the Windows PC special software that allows Windows to read Mac-formatted disks. This software is called MacDrive, costs $50, and can be purchased at mediafour.com.

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.

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