I have a small network comprising an IMac (250GB), a MacBook Pro (500GB) and a PC (200GB), with the PC connected to an external backup drive of 500GB. With the external backup being smaller than the total capacity of my 3 machines, I'm obviously having trouble! So I've bought an additional 1.5TB drive which is also connected to the PC. I try not to keep any critical data on any machine, but network error or user error does occasionally leave critical data in the wrong place. Time machine or alternative PC based syncing software seems to back up from A to B, but I need to backup A/B/C, to D, and then to E (where D holds all critical data, and E holds a back up of all critical data and also a vast amount of non critical information). I'm really stuck trying to find the most robust and elegant backup solution - what I have is clumsy and manual, and that's no good when you're tying to protect client data against hardware failure and user error. Can you help with a better solution?