I have a RAID-0 setup, and as far as I know... its not possible to just use one partition per drive.
Both drives have to be raided as a whole. The performance isnt anything to write home about either. In fact, when I get my new WD SE drives, I wont be raiding them.
AthlonXP1900+@2100+, Abit KR7A-Raid, Radeon 9700 Pro (core370/mem666), 256Megs PC2100, 2x 40gig WD7200, Soundblaster Audigy Platinum, KDS VS 19" CRT, Klipsch ProMedia 5.1s, Creative 12x DVD, TDK 24x CDRW, 500Watt PSU, Win2kSP3.