Revo Free will work on 64-bit systems, but it won't 'see' 64-bit programs.
Advanced Uninstaller 64-bit Free by Innovative Solutions seems to work well with my Windows 7 64-bit installation and 'sees' everything.
It has a lot of the same functionality that Revo has plus it is able to Monitor installations (optional) so a truly complete un-install can be accomplished.
Here's the link: Advanced Uninstaller FREE 64-bit download - X 64-bit Download
Acronis (before 2011) was troublesome for me. I recently bought their upgrade to 2011 and haven't had any problems since.
It seems a required snapman.dll was causing me BSOD's before the upgrade.
Searching around the internet has shown me that I wasn't the only one with that same problem on Windows 7.
Hope this helps some...