Can't install Boot Camp 3.0 on Vista 64 partition-why?

I recently installed SL and was trying to upgrade my Boot Camp version to 3.0. When I run the installer (in Vista Home Premium 64), it closes with the message "Boot Camp x64 is not supported on this computer." I don't see why that would be. The Computer reports that the machine is indeed running in Vista-64. The Mac Pro is version 2.1

Vista Desktop, won't do any good in Mac. I keep installers in one of the Downloads folders.
Navigate into "Drivers" folder and look for Apple and BootCampx64 is what I ran. I copied into "Apple Software" folder:
H:\Downloads\Apple Software\Boot Camp\Drivers\Apple
BootCamp64 - that is the file, not "Setup" that I ran.
I haven't used Vista in 9 months, in Properties -> Compatibility change that to run as admin and see what you can do. In W7 there is "troubleshoot compatibility mode" when Ctl + Clk on a program/installers.
Apple's lack of support means no 64-bit mode in OS X, no support for Windows 64-bit, difficulty booting from 64-bit Vista SP1 or later including Windows 7. So I gave up and built some PCs just to run Windows 7 and do some testing. Even install there and then just move the hard drive over to my Mac Pro to run Windows there!