Regshot is an open-source (LGPL) registry compare utility that allows you to quickly take a snapshot of your registry and then compare it with a second one - done after doing system changes or installing a new software product.
This is a mirror repository of the original project providing x86 and x64 versions built with WDK (you can use MSVC 2010 or even GCC if you like). Every change is committed in the SourceForge repository.
Windows 2000, XP, Vista, 7 both 32-bit and 64-bit
(if you don't build Regshot with WDK, then Windows 2000 is not supported)