SSD's are so fast that a RAID would in fact saturate the Sata 6Gbps interface and quite possibly bottleneck. if all you're using it for is quick windows start up or gaming 1 SSD's speed is more than enough a decent SSD is reading at close to 570MB/s and writing at just a shade over 500MB/s a RAID isn't going to make that much faster.
You really won't see much of an increase. Raid works best with large files, and an OS is made up of a lot of small files. You also run the risk of data loss because as a raid 0 stripe(across 2 drives) if 1 drive fails, you loose the data that was on both drives - even on the one that still works. In my opinion, you're better off just installing them as 2 seperate drives.
thx for the input.
SSD will dramatically improve boot times, but RAID doesn't make it any better. THG did a article to that fact.
SSD DO NOT speed up gaming. Only loading maps (i.e. reading from disk).