I am not 100% sure you can have the startup volume on the raid setup. Also, if you are starting up on the raid volume, your performance will take a hit for sure. Your best bet is to get a firewire 800 HD and stick a 40 or 60GB HD in it and boot of the external drive and set up the two internal drives in a raid 0 or 3 configuration. 0 for speed and performance, or 3 for parity and safety.