I highly recommend you use one of two solutions from Faronics, although I think DeepFreeze will likey work the best for you if the patients need to install software (I have clients using DeepFreeze at a number of locations, and a simple reboot wipes out all changes including newly installed software including viruses and SpyWare, so if the patient makes a really big mess of the system, then a simple restart, reboot, or power cycle will solve the problem immediately -- this also makes it an ideal candidate for your support staff who may not be computer-literate):
Faronics Anti-Executable ensures total endpoint productivity by only allowing approved applications to run on a computer or server. Any other programs, whether they are unwanted, unlicensed, or simply unnecessary, are blocked from ever executing.
Anti-Executable's ability to enforce total compliance provides absolute peace of mind. Organizations benefit from productive user sessions each and every time, while I.T. personnel are guaranteed that desktop computers, notebooks, and servers are compliant with acceptable use policies, regulatory requirements, and software deployment schedules.
Faronics Deep Freeze
Faronics Deep Freeze helps eliminate workstation damage and downtime by making computer configurations indestructible. Once Deep Freeze is installed on a workstation, any changes made to the computer, regardless of whether they are accidental or malicious, are never permanent. Deep Freeze provides immediate immunity from many of the problems that plague computers today -- inevitable configuration drift, accidental system misconfiguration, malicious software activity, and incidental system degradation.
Deep Freeze ensures computers are absolutely bulletproof, even when users have full access to system software and settings. Users get to enjoy a pristine and unrestricted computing experience, while I.T. personnel are freed from tedious helpdesk requests, constant system maintenance, and continuous configuration drift.