I want to incorporate a WD external unit as part of our backup. Currently, we have a dogs-breakfast of gear: Windows Server 2003 system (soon to be migrated to 2008/12) some Macs boot-camp’d to XP Pro and some straight-up PCs. There MAY be a Mac Pro with Parallels some time soon, but we aren’t sure about that. Is there one WD external unit that can handle all this? Total BU volume will be somewhere around 5-600 Gb. but the Server is the big one of course.