A somewhat hypothetical question

I have a Dell Precision desktop which has a RAID disk controller and two 500gb SAS drives in it. It was set up without the RAID enabled from the factory. Dell tech support says that if I enable RAID it will lose the contents of both disk drives.

Sooo ............  it seems like I should be able to back up the C: drive with Ghost 15 and then restore it after I enable RAID. The D: drive has nothing of real value on it and I have a 300gb SATA drive (E:) in this PC that has enough free space to store a backup image. I also have made a custom recovery CD for this computer.

I would like to do this without any surprises and not lose anything currently on the C: drive. It seems simple enough, but I want to be sure that I didn't overlook something. Any suggestions what would be the best way to approach this??