If you like being able to view .PSD files in windows explorer as a thumbnail of the actual image, instead of just an icon, give THIS a shot. I missed this ability since upgrading to a 64bit O/S, my old reg hack no longer worked.
It's working great on Windows 7 Ultimate x64 now. Make sure you grab the correct version for your O/S, either x86 (32bit) or x64 (64bit). The change will take place on restarting your PC.