Dual boot using Deep Freeze on both drives?

How to dual boot XP Pro and Win 7, on 2 separate drives, using Deep Freeze on both drives?

Here is what I want to do. Install XP on one drive, I have done this already. Disconnect this drive and install Win 7 on the other drive. I want to use the bio's to choose the boot order. I spoke to a rep for Deep Freeze and was told that DF would work on both drives as long as C: drive of the unbooted drive is not visible.
I have not installed Win7 at this time. Does anyone know if the other OS, unbooted, drive C: is visible? Also, if it is, is there a way to hide the C: drive from the booted OS?

XP Pro currently installed on SATA 300gig, with 2 partitions, XP Pro on 75 gig partition, aslo installed is a 1 TB SATA.
Win 7 & to be installed on primary IDE 300 gig