Jimellow, the biggest compatibility concern is the this: Newer drives are Serial ATA (SATA), older drives like yours are Parallel ATA (PATA). The SATA drives will not work in your computer. Well, you can get an adapter, but I don't recommend that.
Here's a Newegg link:
Newegg.com - Western Digital Caviar Blue WD2500AAJB 250GB 7200 RPM 8MB Cache IDE Ultra ATA100 3.5" Internal Hard Drive -Bare Drive
Good price, and probably much larger than the old drive. I, of course, can't guarantee that the drive will work in that old of a computer, but it should.
Best of luck!