Oh my GAWD I cannot believe this.
The Raptor is hardly a server product. It's an enthusiasts product labeled as an Enterprise market. I don't know of any Enterprise that would use such a product for anything other than a kiosk or single user desktop PC.
Second, Adaptec is hardly the best HBA. Their performance is pitiful at best. In some cases, their RAID0 read speeds are the same and LOWER than a single drive. It's like JBOD with stripes! :Q
Now that this is out of the way, there are several HBA's with decent performance available. If you plan to use all five disks in the system forget about hitching them to an HBA stuck in 32/33 land. They will sit there and spin and spin and that is about.
Time to start thinking about a real workstation board with PCI-X 133MHz OR purchase a PCI-E based SATA intelligent HBA when they become available.
Cheers!