Absent a feature like Vista's volume shadow feature, is it even possible to get a consistent and complete backup of a live Windows XP NTFS volume? At this point, I'm leaning toward setting them up to only backup the user directory rather than the whole system. I'd coach them to kill their mail apps when they weren't using them, but otherwise the backups would appear to run on autopilot.

This leads to one issue with the "painless" part. I want the backups to go to an external USB hard drive. So far as I can tell, all the tools want you to specify the drive by its drive letter. This seems like a recipe for flakiness, unless I can reserve a particular drive letter for a particular drive, regardless of what order different USB thumb drives and whatnot get connected and disconnected from the system.

It appears that the USB Drive Letter Manager can solve this particular problem. I could even have these USB drives show up with Unix-ish mountpoints in the filesystem rather than drive letters. Anybody try this thing? Is there something built into XP that can have a similar effect?