I upgraded from 32-bit to 64-bit Windows 7 a little more than the year ago. Only I purchased a new computer and installed Lightroom, my old catalog and supporting files, as well as all of my images. I experienced no trouble whatsoever. The images went on a differently identified internal drive, and I had to point Lightroom to the appropriate folder. But that was effortless. I suggest that you have your images organized so that they are all within as few main folders as possible. It will make any reconnecting much simpler.