I built a new PC and put 32 bit XP on its partitioned hard drive. To play with 7 I've been thinking about buying another hard drive and loading 7 on it. Would there be a problem with running 64 bit 7 on the same computer? IOW would there be problems reading/writing to the XP drive?
The answer to both questions is that you would have no problems. I run Windows 2000, XP-64, Windows 7-64, and Fedora10 on the same computer. The Windows installations can't see the Fedora drive, but otherwise everything works just fine.