 <p>Vista has some <a href="http://en.wikipedia.org/wiki/Windows_Registry#Registry_virtualization" rel="nofollow">virtualization</a> support.</p> <p>One thing that you could do for keys under <a href="http://en.wikipedia.org/wiki/Windows_Registry#HKEY_CURRENT_USER_.28HKCU.29" rel="nofollow">HKCU</a> is create a new user profile and run the app with matching credentials in order to force usage of a specific <a href="http://en.wikipedia.org/wiki/Windows_Registry#HKEY_CURRENT_USER_.28HKCU.29" rel="nofollow">HKCU</a>.</p> <p>If you are feeling brave have a look at the registry <a href="http://www.wotsit.org/list.asp?search=registry&amp;button=GO!" rel="nofollow">file format</a>.</p> <p><strong>Edit:</strong></p> <p><a href="http://www.sandboxie.com/" rel="nofollow">Sandboxie</a> looks interesting. Registry specific <a href="http://www.sandboxie.com/index.php?SandboxHierarchy#keys" rel="nofollow">features</a> </p>