One of my coworkers ran out of ideas for Christmas presents for his sisters one year.

So instead of buying them jewelry they probably wouldn't want, or clothes that wouldn't fit or they just wouldn't like so they'd have to take them back, he bought a bunch of computer parts. Then he upgraded their systems. The next year, he did the same thing. And again the next. Within a couple of years, they had really nice systems. And the systems stayed nice, since most people can stay really happy with a computer that gets $100 worth of hardware upgrades every year.

This year, he got married. And his wife didn't like that idea. They needed to buy something, well, gift-y for his family. So she made her intentions known.

His sisters wasn't very happy with the idea. It turns out they like it when he upgrades their computers for them.

So there's an idea to float. Not everyone will love it, but probably a lot of people will. And you can get a lot of nice upgrades for not a lot of money, especially if you know where to shop. Some hints: It's hard to beat Newegg.com for new stuff. And it's hard to beat Compgeeks.com for closeout stuff. And let's face it, unless someone's ripping DVD movies, there's little noticeable difference between a 12X DVD-ROM on closeout and a 16X DVD-ROM from a retail joint. And while an enthusiast will look down on a 20X or 24X CD-RW drive, they cost half as much (or less) than the current state-of-the-art, they're more than half as fast, and to someone used to dubbing from CD to cassette, burning a 74-minute music CD in less than 10 minutes seems really fast.

For me, the magic number is somewhere around $100. For you it might be more like $50. Even if it is $50, there's a fair bit you can do. You'll never run out of ideas.

CD-RW drives. I recently paid $30something for a Yamaha 20/10/40 drive. With Nero software. I love it. CD-RW drives are commodities now; look for a drive with some kind of buffer underrun protection and Nero software. Other than that, buy on price.

DVD drives. A bare DVD drive can cost as little as $30. I believe you can even get by without buying a drive with bundled decoder software--n.player ought to do the job for them. I need to build up a bare Windows box, pop in my DVD drive, and try n.player out to know for sure. If you want to be safe, you can get a decent drive with WinDVD bundled for $40.

Memory. Memory's cheap. It doesn't seem like anybody ever has enough. No-brainer.

Video card. My sister doesn't need a fire-breathing video card and yours probably doesn't either. But a lot of systems have really underpowered cards, way worse than the $25 specials you'll find on Newegg. If you get one with TV-outs, you gain the option to take the PC into the living room to show slideshows on the TV's bigger screen, or watch movies on DVD.

Motherboard. A motherboard swap can be hairier, but if the computer already has lots of cool gadgets, that would make a nice upgrade. You could grab something like a Shuttle AK32L that can take a cheap Duron CPU and works with either SDRAM or DDR memory. That would allow you to re-use the existing memory, and slide in under the $100 mark. Then next year's upgrade could be DDR memory and a really fast Athlon XP CPU, which will be dirt cheap by then.

Scanners. Everyone wants a scanner, and it's easy to find a decent scanner for $50. Look for color depth over resolution--what's the point in having a scanner with higher resolution than your printer? Besides, a lot of scans will be e-mailed. The resolution of your monitor is 75 dpi. High color depth gives you better color accuracy, and thus, better scans.

Digital cameras. Cheap sub-megapixel, fixed-focus digital cameras--the Polaroids of the early aughts--start in the $50 price range too. They're no good for serious shots, but they're fun, and for family snapshots you'll be e-mailing around, they're fine.

And if you're really careful, you can get a decent digital camera--one with more than a megapixel of resolution and a zoom--for a little over $100. Next year for $100-$125, you may be able to get a 3-megapixel digital camera.

DVD burners. They're way too expensive now, but at some point DVD burners will hit the $100 mark. Work on stuff lower on this list. Within two years, the confusion over formats will most likely have worked itself out, and pricing should be along the lines of what CD-RW drives cost now. Remember, two years ago a $50 CD-RW was unimaginable. Today it makes you yawn.

Hard drives. There's always the potential hard drive upgrade. Today, $100 buys what was an unbelievable amount of disk space a year ago. Next year, $100 will buy what's an unbelievable amount of disk space today. Keep your relatives on a three-year upgrade cycle on their hard drives to minimize the probability of data loss, and to keep the computer running briskly. Mark my words: Changing hard drives will soon become the computerized equivalent of an oil change.

I told you you wouldn't run out of ideas. You'll have to repeat some steps earlier in the cycle long before you complete it.