I had the exact same question a few weeks ago (actually, I was set on a RAID0 set-up, but went the SSD route - couldn't be more pleased).
Check out this thread, Need Advice for new HD (RAID0 Use)
, it has tons of good from other users.
I went with the OCZ Vertex 30GB. Here are some of my specs / results (on the comparison, I was previously using a WD Caviar Blue for my boot drive - the other specs are for my Seagate 7200.12 that I use for storage, just for comparison):OCZ Vertex 30GB (Boot Drive) Seagate 7200.12 1TB (Storage Drive)