Western Digital has some boot sector overlay stuff that allows you to use a bigger drive on an older BIOS I had an 80g running in an old P1 a couple years ago.
I've got some real old dogs on my network still doing various little jobs.
My usual "recipe" for upgrading a really old machine for a "new life" is.
Bring the RAM up to at least 512 (1g prefered)
Stick a 20, 40, or 80g drive in it.
Do a format and clean install of XP-Pro, DirectX 9c, Media Player 10, Acrobat reader, and Office 2000 or later.
Replace the CD-Rom with a DVD-ROM - add Power DVD.
And if possible give it a GeForce 2 MX-400 (64mb) video card - and an SB Live 5.1
Using Ebay you can do all the hardware upgrades for under $100 usually.
If you wanna go all out, GEARXS sells 450w PowMax gamers cases for $45 on Ebay. And old clam of a machine
just looks like more in a new pretty case.
Then just run it LEAN - with minimal (or no) background craplets. 512 is plenty of XP RAM if you don't overdo it.
I can get it down to 19 processes or less after bootup easily.
Except for higher-end gaming.... you really can't tell the difference.
Even a lowly P2-400mhz configured as above can do stutter free DVD playback or YouTube stuff, I just did one up for a friend.
Other tips: If you're behind a good firewall and aren't too worried about high security, load XP SP1 because SP2 has a lot of bloat in it and slows down an older machine. And forget the 2 hours worth of updates. SP1 as installed is very stable right outta the box - at least the version I have is.
Then when it first boots after install I disable internet time (in the clock), automatic updates, and task scheduler. THEN I go into Administrative tools > Services, and set Automatic Updates, Task Sheduler, and Windows Time (synchs network time) all to MANUAL and stop the services. And reboot. Then comes all the drivers and programs and stuff.
-W