Since you are looking to get 100gb drive, then you are down to these choices:
WD 1200BB 120gb - Best bang for the buck, IMO.
WD 1200JB 120gb - Can't find a better IDE drive when it comes to performance.
IBM 120GXP 120gb - Performs close to the 1200JB, but IBM now has a bad rep, so you make the call.
If you can go down to a 80gb drive, then:
Seagate Barracuda IV 80gb - Quietest drive around.
Maxtor D740X 80gb - Performs very well, ATA133.