I have both the main computers that I use converted to Windows 7 x64 now.  On the one, I have an adaptec SCSI card that is not recognized, but both systems are working at this point in time.

After waiting for 7 days for the slow computer to do an upgrade from Vista x32 to Windows 7 x32, I just did a reload instead.  The reload completed successfully in under an hour and a half (I was patient because even after a week, the installer was still animating but -- there's a limit to how long I was going to give it, especially since the computer had not had a clean install for many, many, many releases of Windows).

It's up and happy on both of the computers here.