All of the applications you listed have default save directories.  I'd
recommend setting up a client option set to backup only those directories,
then, when the users get their machines, they should also get a document to
sign saying something to the effect of "Any data I save outside the
established default directories (and you can list them here) will not be
backed up, and I accept the risk to that data," and a signature line at the
bottom.  This comes back to you and gets saved somewhere.  Once they sign
off, then you can let them run their backups.

Two other things I'd add.  One, since you have a group that would clone
machines for a full restore, I'd probably also eliminate the System Object
from the domain - it's 200-400MB of data you don't need backed up, since
you'd be able to reclone and restore the whole system.  Two, don't forget
to backup their Internet Explorer Favorites (or Netscape bookmark file).
I've seen some people get very upset when that type of data is lost.

Nick Cassimatis
nickpc AT us.ibm DOT com

Think twice, type once.