RAID is a dangerous game for most folks to play. Just make sure you do a ton of homework to determine if it is really the route you want to take. I would take a look at the ATI 4850 cards and this motherboard over what you have listed now:
Newegg.com - ASUS P5Q Pro LGA 775 Intel P45 ATX Intel Motherboard - Intel Motherboards
You will probably save a few bucks and get more out of it.