<< i want 2x cheetahs (15k, u160) in raid 0 and 1x cheetah (10k, u160) not in raid >>
Boot off the 10k drive and stripe the two 15k drives within the OS. This works well. A RAID card is only necessary if the Operating System doesn't support striping and/or you only have two drives and would like to boot from the array.
Cheers!