Troubleshooting a system with RAID 5 and 500GB drives

I have a system with RAID 5 built into the motherboard with three 500GB drives and I am not sure how to go about troubleshooting the system. It has failed and I cannot get into the system. Can’t even reload OS as it won’t recognize the disk either.
What to do at this point? The Board is an ASUS, 4GB mem. Vista Ultimate OS.