Time Capsule Set Up

[winston1888]

Hi, i'm looking for a little advise regarding back ups.
I have just bought ma first Macs, a 160Gb late 2009 mini used mainly as a music server for itunes. I have a seperate 650GB hard drive which stores all my audio files, nothing is stored on the mac as the volume has already exceeded the 160GB.
I'd considering buying 2 1TB drives and storing all the music on these. Is it possible for time capsule to back up 1 HDD to another or does the primary drive have to be the minis internal drive. I'll be using a firewire drive to connect the mini. Ideally the drives would be firewire or USB powered as i'm running out of power points and itunes defaulting to the macs internal drive when the HDD isnt powered up is in a nuisance.
To complicate thing slightly i have just bough a new 500Gb imac which is used for general computing and storing photographs, video, etc. This is also backed up by a external hard dive and time capsule seems to be operating ok on this sytem. my second question is should i consider a wireless network drive to back up both macs or is it better to keep them completely seperate.
Am i on the right track or is there a simpler solution i'm too dumb to see?