As for your original question about RAID drivers with Vista it is very easy because Vista will recognize your flash drive, read this
. As for XP I could be wrong but the best way to do it I've found is to slipsteam the XP install disk with the raid drivers, read this
. I have slipstreamed a copy of XP for my backup system and it's a great thing to do anyways because you can put all the service packs and hot fixes on there and have them install with the OS.