Microsoft is pushing the envelope once again in preparation for a complete transition to 64-bit computing by making sure all programs running in 32-bit editions would run in 64-bit platforms without any problems. Hardware on the x64 platform should normally use Windows Vista 64 bit editions and consumers should not worry about being left out in the community.
Are there really no worries?
Despite 32-bit applications running in Windows Vista 64 bit versions, consumers should at least know that driver support does not hold true. Vendors should be able to come up with a version working with Windows Vista 64. Aside from that, 16-bit versions does not run in Windows Vista 64-bit versions anymore.
The benefits of running Windows Vista on 64-bit platform includes Data Execution Prevention which prevents exploits and provides defense against buffer overflow attacks; although this might cause problems whenever Vista stops legit applications.
Having said that, I would most likely choose Windows Vista 32-bit applications as it would take more than a year or two before 64-bit becomes a standard. I wouldn’t want to worry about anything from applications to drivers. Would you?