As an experiment, I just resuscitated a Y2K-era notebook with a few inexpensive hardware upgrades, split its hard disk into two 20GB partitions, and installed Windows XP with Service Pack 2 on one and Ubuntu Linux on the other. The results were surprising. (You can read all about it in Linux, XP and my old PC.)
That six-year-old PC turned out to be far from obsolete, which got me thinking about the nature of PC obsolescence.
My first IBM-based computer was built in the early 1980s by a Korean clonemaker and sold under the Leading Edge brand name. It had an Intel 8086 processor running at 8MHz or so and 512K of RAM, if I recall correctly. It had a monochrome monitor, at least one 5.25” floppy drive, and a hard disk whose capacity was measured in some small number of megabytes.
I replaced it with a succession of computers over the next ten years, each with incrementally larger hard disks and slightly faster processors. When I was testing beta versions of Windows 95 (then code-named Chicago) in 1993 and 1994, I was probably using a 33MHz 486 processor with 4MB (or maybe an eye-popping 8MB) of RAM.
Would you expect any of those ancient PCs to be even marginally useful today? Don’t make me laugh. Even the first-generation Pentium 133 and 166 models I spent more than $2000 to purchase in 1996 and 1997 would be nearly useless a mere decade later.
I was able to run the first release of Windows XP (including beta versions from 2000) on PCs built around Intel’s Pentium II series chips from 1998 or so. XP on a 233MHz wasn’t fast, but it worked. I wouldn’t do that today, however, mostly because the cost of the EDO memory chips it used would be prohibitive. It would probably run $100 to bring it up to its max of 192MB!
Basically, I think any computer using the Pentium 3 family or later and built in 1999 or later should probably be usable with Windows XP today, assuming you can find memory upgrades at a reasonable price.
Ed Bott 
Up until last year, I was using an ancient Pentium II machine with 128 MB of memory as my main Linux file and IMAP server, and it performed beautifully. I didn’t even have to disable all the unnecessary daemons. With a suitable swap file it managed memory nicely. I considered upgrading the memory, but the cost was surprising, so I just let it go without.
Ed, this post brings back memories! I too had a Leading Edge computer, which I bought about 1985 or so. At the time, it was a slick little computer, but I cringe to think of how much I spent “in the old days.” I bought a 2-slot HardCard hard drive for it: $600 for 20 MB! Yikes!
I have Windows XP Pro running on a Gateway Pentium 350mhz with 96mb of RAM that my 3 year old daughter uses to play games on the PBS website. It does occasionally lock-up but she really doesn’t seem to notice. It may not be fast, but it does the job.
I have a PC baught in 1998 a P3 450MHz with a 8 GB Hard Disk. I’ve upgraded the memory from 64MB to 384MB and upgraded the integrated video to a 32MB VGA card. Performance is great and I dont know why but it’s more reliable than by new P4 3.4GHz machine.
I know that this is hard to believe but my computer at work is a 486 with 16 MB of memory running win 3.11
It’s sooooo “early nineties”, isn’t it?
I find a lot of old comps in the trash and if they are not too beat up and I can get them to work I throw a copy of winXX on ’em and give them to my friends. I am always amazed at how fast an initial install of ‘XX’ boots up on a 166 with 32 mb RAM 🙂 Faster than my XP Pro (but then I am a freeware program junkie). I love older computers, something so clean and simple about them and they seem to last forever….. and winXX still does the job it was designed for: communication, entertainment and information gathering.
The lady who had the 166 just got a ‘new’ (to her) 300MHz Compaq (forget how much RAM, maybe 64) from me and I can’t convince her to part with it for a faster model that will run XP. So what else do you need for email, checking the bank statement and getting recipes from FoodTV.com?