I just added a new Hard Drive

I don't suppose you happen to have any other SATA ports on your motherboard? Some of them have another set of SATA ports attached to a different controller. For example, on mine, SATA6 and SATA7 are separate from the others and controlled by a different chip, and SATA8 and SATA9 are controlled by yet a third. If you have a motherboard like that, you should be able to leave your primary drive the way it is (with RAID turned on), and just plug your new drive into one of those other ports.