There are two fire extinguishers in my home, and I replace both when they become out of date, even though I've never used them. Believe me, the cost of keeping them in order is a bargain when you need a fire extinguisher.

There are virtual fire extinguishers for computing. Like the real ones, they are seldom used. But when they are needed, there's no substitute.

I'll put on my brimmed fire chief's hat and take a look at some high-tech fire extinguishers that I want you to have around. If you're lucky, you'll never need them.

We'll start with something called "restore points," a built-in feature of Windows. It's gotten me out of more jams than I can list. Basically, it returns the computer to a point in the past when everything was working fine. So it's not only a fire extinguisher, but also a time machine. See how to use it at http://tinyurl.com/253en.

Backups: If you're not regularly backing up data in your computer, you are walking around with a "kick me" sign on your back. Hard disks die — it's guaranteed if you use them long enough. Get a brand-name external hard disk and set it up to automatically back up your computer at least once a week. Vista has built-in software for this. Otherwise, you can use software that comes with the disk or a separate program.

Rescue software: Sooner or later, you will delete the wrong file and empty the trash prematurely. Or an important file will be damaged. Or your hard disk will malfunction, leaving important files beyond reach. There are programs — some free — that can help:

n http://www.objectrescue.com/products/filerescuepro/.

n http://www.nucleusdatarecovery.org/.

n http://downloads.zdnet.com/abstract.aspx?docid=226952.

UPS: It's short for uninterruptible power supply. Once limited to business users, it is now fairly common in most homes. I recommend you follow suit. If the power goes out, your UPS furnishes enough steam to allow you to save the data on your computer and shut it down.

It also protects your computer against bumps in the voltage or brief brownouts. I connect my router and DSL modem to my UPS. That way, a blip in power doesn't knock me offline. At $100 or so, it's good insurance. I like the APC brand.

UPS, part two: For those of you who read the item above and thought, "Well, of course I have a UPS, who doesn't," here's something to double-check. If your UPS is more than 3 years old, the battery is probably on its last legs. Either replace the battery or buy a new UPS.

Junk box: Try to keep some spare ethernet cables, USB cables, a mouse, a video card you've discarded and other potential replacements on hand. Computers have an amazing knack for going out when no help is available and when you really must finish a project. Your junk box is your friend.

An old computer: Yes, you heard me right. Most of us replace PCs many times. The old computer is worth almost nothing as far as cash value. But as a temporary replacement late on a Sunday afternoon when computing work must be done: priceless. Besides having a workhorse ready to go, you avoid any potential dangers of having others grab your data off a discarded PC's hard disk.

Discs and manuals: It's only when a hard disk crashes that most of us discover that a program disc is missing. So take stock of them occasionally. If your programs require activation codes, make sure that you have the code and manual. I keep all this in a single area of my home office bookshelf. Understand that your backup only contains the data you created; programs themselves should be installed from original discs.

Finally, it would not be crazy to include a real fire extinguisher in your computing room. After all, not all fires occur in the virtual world.

— Bill Husted writes for the Atlanta Journal-Constitution. E-mail: bhusted@ajc.com.