The OS drive wants to do lots of short reads and writes. The velociraptor excels there. Raid-0 does well with large blocks of sequential data; a much different pattern.
There is generally no real world(vs. synthetic transfer rate benchmarks) performance advantage to raid of any kind.
Go to www.storagereview.com at this link: http://faq.storagereview.com/tiki-index.php?page=SingleDriveVsRaid0
There are some specific applications that will benefit, but
gaming is not one of them. Even if you have an application which reads one input file sequentially, and writes
it out, you will perform about as well by putting the input on one drive, and the output on the other.