PC Magazine has a feature about inexpensive PC upgrades. There's some good advice there, but some questionable advice too. Since I really did write the book on free and inexpensive upgrades, I'll present my own advice (but I'll skip the pretty pictures).

Hard drives

The best upgrade they didn't mention is replacing the hard drive. I've been squeezing extra life out of old systems for years by taking out the aging drives and replacing them with something newer and faster. The trick is figuring out whether the drive is the old-style parallel ATA (with a 40- or 80-conductor cable) or newer SATA. If you can afford it, it makes sense to upgrade to a SATA controller so you can use a more modern drive. Newer drives are almost always faster than older drives if only because the density of the data is always increasing. If a drive stores twice as much data in the same linear space as an old one, it (roughly) means it will retrieve the data twice as fast, assuming the disk spins at the same speed (and it may spin faster). You can go all the way up to the 10,000 RPM Western Digital Raptor drives if you want, but even putting a mid-range drive in an old PC will speed it up.

Some people will point out that a new drive may be able to deliver data at a faster rate than an old controller in an old PC can handle. I don't see that as a problem. There's no drive on the market that can keep a 133 MB/sec bus saturated 100% of the time, and the old drive certainly isn't. Even if your older, slower bus is the limiting factor some of the time, you're still getting the benefit of a newer drive's faster seek times and faster average data transfers.

While replacing a hard drive can bust an entire $125 upgrade budget in and of itself, it's still something I recommend doing. Unless your system is really short on memory or you're heavily into gaming, the hard drive is the best bang for your upgrade buck.

Memory

The other point I disagree with most strongly is the memory. There's very little reason anymore to run a system with less than 1 GB of RAM. As a system becomes more obsolete, memory prices go up instead of down, so it makes sense to just install a ton of memory when you're upgrading it anyway. If you need it later, it will probably cost more.

The caveat here is that it makes very little sense to install 4 GB of RAM, since the Intel x86 processor architecture reserves most of the 4 GB block for system use. If you install 4 GB of RAM, you really get more like 3.2 or 3.5 GB of usable memory unless you're running 64-bit Windows. I don't recommend going 64-bit yet. When it works, it works well. Unfortunately there's no way to know if you'll have good drivers for everything in your system until you try it. I wouldn't go 64-bit until some popular software that requires (or at least takes really good advantage of) 64 bit arrives. The next version of Photoshop will help, but I think the thing that will really drive 64-bit is when id software releases a game that needs it. Until then, hardware makers will treat 64-bit Windows as an afterthought.

I usually put 2 GB of RAM in a system if it'll take that much. If you do a lot of graphics or video work, more is better of course. For routine use, 2 GB is more than adequate, yet affordable. If a system won't take 2 GB, then it makes sense to install as much as it will take, whether that's 1 GB or 512 MB. If a system won't take 512 MB, then it's old enough that it makes sense to start talking replacement.

Outright replacement

Speaking of that, outright replacement can be a very practical option, especially if a system is getting up in years. My primary system is a 5-year-old office PC. Take a 2-ish GHz P4 or equivalent (current market value: $75-$125), load it up with 2 GB of RAM and a moderately fast hard drive, and you'll have a better-built system than any $399 budget PC on the market. It will probably run as fast or faster, and it will cost less.

I have two PCs at the office: a 3 GHz Pentium D, and a 2.6 GHz Core Duo. Both have 2 GB of RAM. They theoretically encode MP3s faster than my home PC and would make better gaming PCs than my home PC (ahem), but for the things I do--namely, web browsing, spreadsheets, word processing, e-mail, and the occasional non-3D game--I can't tell much difference between them. The System Idle Process gets the overwhelming majority of the CPU time on all of them. Other upgrades

The other things discussed in the article can be worthwhile, but faster network cards won't help your Internet speed. If you routinely copy huge files between multiple PCs, they help a lot, but how many people really do that on a regular basis?

Fast DVD burners are nice and they're inexpensive, but if you needed one, you'd know it. If you don't know what you'd do with one, skip it. Or if you have an older one that you use occasionally, you probably won't use a faster one any more often.

For $60 you can get a decently fast hard drive, and that will do a lot more for overall system performance than either a network card or DVD burner upgrade.

The video card is a sensible upgrade under two circumstances: If you're using the integrated video on your motherboard, or if you play 3D games and they feel jerky. If neither of those describes you, skip the video card upgrade.

Free upgrades

The article describes CHKDSK as a "low level defrag." That's not what CHKDSK does--it checks your drive for errors and tries to fix them. If your drives are formatted NTFS (and they probably are), routinely running CHKDSK isn't going to do much for you. If you run CHKDSK routinely and it actually says it's done something when it finishes, you have bigger problems and what you really need is a new hard drive.

If you want to defragment optimally, download JK-Defrag. It's free and open source, and not only does a better job than the utility that comes with Windows, but it does a better job than most of the for-pay utilities too.

The first time you run it, I recommend running it from the command line, exactly like this: JkDefrag.exe -a 7 -d 2 -q c:. After that, just run it without any options, about once a month or two. (Running more often than that doesn't do much good--in fact, the people who defragment their drives once a day or once a week seem to have more problems.) Run it with the options about once a year. Depending on what condition your system is in, the difference in performance after running it ranges from noticeable to stunning.