The only other detail here is that the Megaraid card is in the 32 bit PCI slot. For some reason I can't boot the machine with the Megaraid card in the 64 bit slot.
What's kind of motherboard are you using? Have you flash your RAID card with the latest BIOS. I did so on my 320-1 card and I believe it made it compatible with the latest driver.
-eric wood