As others have stated.. Promise cards are crap.. I recently built an array for my home server using 5x 300GB sata drives on a couple of cheap 4 port silicon image cards. I decided to bypass all the mucking around with raid boards, and just build the array using linux software raid. The box does very little more than push files to a couple other machines, so I built it out of an old dual athlon I had around.
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80gig red mk2 -- 080000125
(No, I don't actually hate Alan Cox)