One of the most common search engine hits on this site involves the words "emachine" and "upgrade" or "upgrades."

There are a number of things to keep in mind. Some of this advice also holds for low-end units from Compaq and Gateway and the like as well.

First things first: eMachines don't have the best reputation. The majority of their problems are due to the power supply though. Aftermarket replacements are readily available, and I recommend them. Don't buy a factory replacement; it'll just fail again like the original. A quality replacement from Sparkle or PC Power & Cooling will run you less than $50. I've seen 180-watt Sparkles go for $35. The stock 145-watt unit isn't very adequate and isn't of the utmost quality. If I bought an eMachine, I'd buy an aftermarket power supply and install it as soon as I could. I wouldn't wait for the factory unit to fail.

If I had an eMachine I wanted to upgrade, I'd track down a PCI video card. The problem with integrated video on a lot of motherboards is that the CPU and video chip have to share memory bandwidth. What's that mean? Part of the time, your nice 64-bit memory bus is reduced to 32 bits, that's what. Steve DeLassus told me a couple of years ago about putting a cheap PCI ATI video card in his wife's Compaq, which had integrated video, and everything about the system sped up, dramatically. I made fun of him. But it wasn't his imagination. I was wrong, and the explanation is simple: After he disabled the onboard video, he finally got the computing power they paid for.

Besides that, any add-on card is going to be faster than the integrated video in anything but an nVidia chipset anyway. Last I checked, eMachines weren't using nVidia nForce chipsets for anything. If you're into 3D gaming, you shouldn't have bought an eMachine in the first place, but look for a PCI card with an nVidia chipset. If you're just into word processing and e-mail, something like an ATI Xpert98 will do nicely. Yeah, it's an old card, but it's still more than adequate for 2D applications, and it's cheap.

If you're wondering if your system's integrated video is holding you back, the best tell-tale sign to look for is called "shared memory." Enter your PC's setup program and look for an adjustable amount of shared memory. If you find that setting, you'll almost certainly benefit from disabling it and plugging in a video card.

The next thing I'd look to do is replace the hard drive. Hard drive speed is significant, and sub-$500 PCs don't come with blazing drives. Pick up a 7200-rpm drive of adequate capacity. They're not expensive--you can be in business for under a hundred bucks. The performance difference is dramatic. Most retail-boxed drives even come with all the software you need to move all your data to the new drive. CompUSA frequently has something on sale. I prefer Maxtor drives over Western Digital because they're faster and more reliable; CompUSA's house-brand drives are just repackaged Maxtors, so those are fine as long as you can find a 7200-rpm model.

The modems that came in eMachines are worthless. If you don't have broadband yet, replace it with a USRobotics 2977 modem immediately. That factory modem is costing you 35% of your CPU power. The USR will give that back, give you better throughput on top of it, and costs $40 at newegg.com. Good deal. But don't settle for anything less than that--any modem that costs less than $40 is going to have the same problems as the factory modem.

Most eMachines can take more memory, but a lot of eMachines already shipped with adequate memory. There's rarely any reason to put more than 256 MB in a PC. If your machine doesn't have 256 megs, you can pick up a 256-meg stick pretty cheaply.

Most eMachines can take a faster processor, but I rarely bother. Unless you can increase your clock speed by 50%, you're not likely to really notice the difference. Doubling is better. You'll get better results from adding a video card and a faster hard drive.

Likewise, a high-end sound card from the likes of Creative or Turtle Beach can reduce the amount of work your CPU has to do and give you much better-sounding audio than what your eMachine has on the motherboard, but is it worth putting a $100 sound card in a computer you paid $399 for?

It's easy to see you can very quickly spend $300 on upgrades for a computer that originally cost $399. That makes it hard to justify, when you could just get a new $399 computer. So should you do it? It depends. Don't spend more than half the price of a new computer to upgrade an old one. But also keep in mind that a new computer won't come with first-rate components, and the aftermarket parts you're buying are first rate, or very close to it. If that PC you're looking to upgrade has a 600 MHz processor or faster, it's likely that when it's upgraded, it'll hold its own with a new computer. In that case, you should think about it.

But if you've got a four-year-old eMachine with a 300 MHz processor in it, you're better off buying something new. When you can buy a 900-MHz PC without an operating system from walmart.com for $299, it's just not worth wasting your time. Load your eMachine's copy of Windows on the new computer and stick the eMachine in a closet somewhere as a spare. Or pony up a couple hundred bucks more to pick up a brand-name PC with Windows and a monitor, then get a couple of network cards and network your computers together. Your family will appreciate being able to share a printer and an Internet connection. If you pay a little extra to get wireless cards, the computers don't even have to be close to each other.

One last thing: A lot of people sniff at eMachines. Yes, they are cheaply made. But they're not all that bad of a machine, aside from the skimpy power supply. Replace it, and you've got a lot of computer for the money. Packard Bell did a lot to ruin the reputation of cheap computers in the 1990s, but the problems they had were mostly due to skimpy power supplies that were odd sizes so there weren't many aftermarket replacements, and due to junky integrated modems and/or combo modem/sound cards that did both jobs poorly, killing system performance and causing software incompatibilities. Today's highly integrated motherboards have eliminated that combo sound/modem problem. I know I malign the company all the time, but in all honesty, once you put real modems and sound cards into Packard Bells, they did OK as long as the power supply held up. I've got an old Packard Bell P120 with Debian Linux loaded on it. I ripped out the sound card/modem combo. I left the power supply alone because it looked decent. The machine's run several years for me without any problems. Of course I covered up the Packard Bell logos on it.

Today, the same holds true of an eMachine--it's just the power supply and video card you have to worry about now.