I just loaded 64-bit Vista Business on my Mac Pro 8-core -- had the same problem.

Try this: Go to Control Panel > User Accounts> User Accounts, then select "Turn User Account Control on or off, then turn off (deselect) "Use User Account Control (UAC)...

This should solve all your file location problems.

BTW, my new Mac Pro is likely the finest PC made for the $$.  This is my first Mac in over a decade, and the build quality is way beyond any other PC workstation for the $$ I paid.  I get 2 8-core boxes (Mac & PC), and 2 4-core 2.8 GHz Xeons, 64-bit Vista, 6GB of RAM, and Vue6I run....*very fast!

...however, I'm not sure Vista Home Premium has this on/off account control feature, as the Business version has?*