Depends on what ur wanting to do with the machine....
Gaming, Video Editing, DataMining, etc., etc.
If u want a 32-bit RAID card the can handle all RAID levels, not just 0/1....go with a AMI ExpressRaid 500 Ultra160 Single Channel w/32meg Battery Backed Cache. (Cards are fast and inexpensive)
If u want a 64-bit RAID card u have quite a few different choices....depends on what speed u wanna go...Ultra2, Ultra160, Ultra320....
Adaptec, AMI/LSI Logic, and Mylex, are the main brands to stick with...
If u just want striping, which is not cached. your best bet is an Adaptec Ultra320 29320-R Card....Not a true raid card, but for striping it will work just as well.
Joe