I don't recommend RAID0 for anything except the fun of fiddling with it. The answer will depend on how much money you have to throw at the problem.
For high-write-rate activity, I actually suggest an SSD. If cash is tight, buy one that is just large enough for one of your longest sessions. After the session completes, copy it to the HDD.
If cash is plentiful, buy an SSD large enough for your OS installation too. Everything will start more snappily. Remember that installing a game on an SSD will make the game / levels load more quickly but have no effect on frame rates.
Could I buy a 60GB SSD, put Win 7 on it, install my game, and record to my HDD? I don't think a 60GB SSD will be enough for my recording. I usually do 20+ minutes which is about 60 gigs.