I wouldn't use any of this registry cleaners at this moment, not until it's reliability is confirmed in Windows 7.
Revo is probably OK (so as Uninstall Tool, very good program, but it's not free), but I think that it would be smart to wait for release that will have official support for Windows 7.
Now, about these registry cleaners... Opinions about them are very different. Some would say that, for example, TuneUP Utilities is excellent application for cleaning registry, some others would strongly disagree and claim that it could ruin your Windows (not talking about Windows 7, but generally).
So, my advice is to wait a little, until new versions of this programs are released.