From my limited experience, I believe your best bet is still a 10K single drive. I use to use a RAID 0, however, problems I encountered, which I believe had to do with a bad sector (which entailed me having to go all the way back to DOS to work around crashes to get back to a single drive) has made me gun-shy of RAIDS. I found when I benchmarked my RAID, while some of the the throughput was indeed fast, the jumping back and forth between drives actually caused fairly significant "valleys" in the performance.
My 2-cents.
Nemo