My first question is, why did you go with the ML370? This is just a suggestion, but the DL380 will do everything the ML370 will do, and it's less than half the size. The only thing you lose is two PCI slots.
If you go with the DL380, it has on onboard ROC chip that will serve your RAID array controller needs just fine.
If you are determined to go with the ML370, I'd suggest you visit
There you will find the "System Configurator" which will allow you to pick any of the Compaq models, and then you can customize EVERYTHING you want, including you can pick a single or dual port array controller. I'd pick the single if that's all you need. It will probably pick something from the 5300 series.
Also, while you're there, compare the DL380. I think you'll like it.
If you don't need redundant power supplies, check on the DL360, smaller yet, and has an integrated remote insight card.