Before Windows 7 64bit came out there were reports from users about RegVac having problems with some third party software. That is why we did not list Windows 7 64bit in the compatibility list.
We were not able to test RegVac in Windows 7 64bit before the official release of Windows 7 (we did not get in on the prerelease beta trials like we had in previous version updates). When we tested it, RegVac did not cause any problems for us. The few specific problems that were reported to us, were not problems that we were able to reproduce. More and more people are reporting that they are not experiencing any problems with RegVac in Windows 7 64bit and so I am considering adding Windows 7 64bit to the compatibility list.
One thing that does not work in RegVac in Windows 7 64bit is the Registry Backup, Pack, and Restore in the Expert Zone. This is a bug in Windows 7 64bit and not a problem with RegVac. When Microsoft fixes Windows 7 64bit (which I doubt they will), then RegVac will work.