I’ve posted a comment on my Coho Tech Blog that describes my reason for staying with the 32-bit OS (instead of upgrading to 64-bit) when I upgrade tomorrow to Windows 7. I discovered that my Canon scanner and PVR-150 TV Tuner card do not have the drivers to work properly on Vista or Windows 7 64-bit. Specifically, the PVR-150 card does have a 64-bit driver but it won’t work properly if your computer system has 4 or more GB of RAM installed (which mine does). The big reason to go to 64-bit is to access more than 3 GB of RAM, so it defeats the purpose of going to 64-bit if you can’t add more RAM!
Since I use my PVR-150 for recording TV shows on daily basis, I’m sticking with the 32-bit OS during the upgrade. So for those planning to jump to a 64-bit OS, I suggest you run the Microsoft Windows 7 Advisor program which will help you identify if some of your devices are incompatible.