That seems a bit rough. I run 64-bit Vista myself, and there certainly is some software which one can't run. I do use VNC Viewer 4 however without any problems, which proves I guess that there's at least one version of this program which will run on x64.
With so many 64-bit processors being sold, it seems logical to have an OS which is also 64-bit to take advantage of it. For some strange reason, we 64-bit Vista users are still on the bleeding edge rather than in the mainstream.