As of time of posting this blog entry, Canon still does not support Vista x64. Here's a trick that I found to work:
1) Install 32-bit Vista drivers. You normally get the EOS Solution disk with your camera body. Just use those.
2) Here is the magical bit... On your camera, change the connection mode from PC Connection to Print/PTP.
3) Now connect your camera to your Vista x64 pc.
Voila! It works like magic. =)