I'm reviving my thread because I got some new info!
I did some googling and found one specific reference to this matter which may be meaningful -- a forum had a post that was Win 64 specific for the registry hack, which was what I was wondering about, and here are the entries he gave for the registry:
Windows Registry Editor Version 5.00
For those who have not done this with your Win7 64 bit system, the instructions are the same as a 32-bit system: paste these lines into a text file, then rename the .txt file with a .reg extension. This makes the file automatically associated to the Registry, so you can double-cick it to "install" these lines into the registry. After that you should be able to install a version of DPP that is listed as supporting Vista 64 bit, such as the 7D software, although I don't believe that DPP will actually be "64 bit" any time soon.
Be forewarned, though, that "hacking" the registry has risks -- if "bad" stuff gets in there it can crash your system -- you'd likey have to do a "safe mode" reboot and try to "unhack" things (or do a System Restore) so do this at your own risk.
Well, try it if you want and post back your results, good bad or ugly!