TEST-RUN looks after the Registry in a different way than providing a Registry backup which could be used to fix the Registry "after" any corruption. Instead, TEST-RUN provides a Separate Registry especially for testing trial programs. After testing a program, you can switch back to your normal Registry and install it, or uninstall it before switching back.
TEST-RUN is very easy to use, and provides you with a visual reminder when you have the special test Registry in place. This program is provided as FREEWARE. There are no secret files written to your hard disk, and no Registry entries made on installation. This series of files requires less than 365kb, and can be cleanly uninstalled by access from the Start Menu or the Desktop.
http://dogkennels.gq.nu/testrun/