Controlling window size on RDP host

We have a secure environment containing extremely sensitive information we
have offshore developers access via RDP from an offshore location. The
offshore personnel are contractors and, while trusted, we try everything in
our power to keep the accessed data on the XP virtual workstation they
connect to. We recently found out that users can resize their window and
'Print Screen', then paste the capture on their PC's. I'm wondering if there
is any way we can prevent resizing of the window on the XP workstation
onshore (force either full screen or full minimize).

Any help with this is extremely helpful! Jacob