Hmm - looks like that board MIGHT have native RAID 5 capability. If not, or you would rather do it with a good card, I'd use this:
http://www.newegg.com/Product/Produc...82E16816103009
You have one PCI-X slot which is what this card requires. Thinking about it a bit more, I'd probably go with the card anyway. It has its own processor and cache ram and it supports SATA II. I've never been terribly impressed with integrated RAID controllers anyway. The card ain't cheap, but nothing for servers is. The Adaptec Storage Manager software is superb.