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 You should also seriously consider buying a new computer, simply because everything else on your machine is also out of date and, as time goes on, you may find that more and more software and Web sites won’t work well with it.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 using cellphones as modems for laptops, storing personal files from office computers and buying an ultralight laptop.

I would like to buy one of the new phones that run on high-speed networks from Verizon or Sprint and use it as a modem with my laptop. Do the phone carriers charge extra for this?

Yes, both Sprint and Verizon do impose an extra monthly charge for using this feature of phones like the new Treo 700p. They reason that if you access the Web on your phone, which has a limited browser and no hard disk to store large downloads, you aren’t likely to use a huge amount of network capacity. But once the phone is used as a modem with a laptop, it becomes very much like their laptop cards, for which they do charge a hefty monthly data fee. For instance, Sprint charges $40-$50 a month extra for unlimited data connections using the Treo 700p as a modem, depending on the length of your contract and whether you also have a Sprint voice plan.

I’m changing jobs after 10 years. What is the best way to take my personal files with me? I know Microsoft Office documents can be readily put on any storage media, but what about emails and contacts stored in Outlook? Can you offer some advice on how to best accomplish this move? (I am not taking any company property.)

Since this isn’t a legal column, I won’t weigh in on what constitutes personal data on a company computer. But it’s pretty easy to move your email and contacts from your Outlook to another copy of Outlook on a new PC at your home or your new office. In Outlook, go to the File menu. Select “Import and Export… “. Choose “Export to a File.” Then select “Personal Folder File (.pst).” Next, choose the Outlook folder containing the data you want to export. This could be your email Inbox, or any other email folder, or it could be the Contacts folder, or any other non-email folder, like Calendar. Finally, select the location where you want to save the exported data. If you are using a USB drive, use the “Browse” button to locate it. Then, hit “Next” and then “Finish.” Repeat the process for each folder you want to export. At the new computer, insert the drive with your exported data, launch Outlook, bring up “Import and Export…” again, and this time select “Import from another program or file.” Follow the steps to import a .pst file.

I am interested in purchasing an ultralight laptop computer for traveling, something I could carry in a messenger bag. I wish to use it mostly for Internet connectivity and word processing. I might even sneak in a DVD for use on the plane. I have looked at the Sony Vaio TX series and the Dell X-1. Are there others in the same size/weight category I should consider?

Yes. You might look at the HP Compaq nc2400 or the Lenovo ThinkPad X60 or the Gateway NX100X or the Toshiba Portégé R200. Except for the HP, none of these has an internal DVD drive, though, so depending on how important that is to you, you might have to spend more or go up to around four pounds. The Sony TX is excellent and combines low weight with an internal DVD. But it’s expensive. Other options for ultralights with internal DVD drives are offered by Fujitsu and Panasonic. I haven’t reviewed all of these, so I can’t recommend them all. My review of the Sony TX is at: http://ptech.wsj.com/archive/ptech-20051006.html. My review of the HP nc2400 is at: http://ptech.wsj.com/archive/ptech-20060518.html. My review of the ThinkPad X60 is at: http://ptech.wsj.com/archive/ptech-20060420.html.

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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