Hello. I am about to make the move from OS9 to OS X (yes, I know, I'm a late starter) and I have just ordered a Mac Pro but have not yet ordered any additional hard drives. I have the basic 640GB drive coming, and intend to install another 640GB drive for audio recording. I also plan to get another one or two drives to back up with. Is it possible to set up time machine to back up the system drive to hard drive number 3 & the audio to hard drive number 4, or do I have to order one, larger capacity drive (1,5TB?) to back up both the system and audio drives? Thanks in advance for any advice.