You could definitely use software RAID if you convert your disks to Dynamic Disks in Windows management, but you'll trade some CPU processing power for the faster hard drive access times.
If you want to do hardware RAID, I'm pretty sure its going to be an all or nothing type thing. But I'm not 100% on that.
If you want to do hardware RAID, I'm pretty sure its going to be an all or nothing type thing. But I'm not 100% on that.