I have the same problem with the AMD Radeon HD 7700. It has supported drivers for vista but after rebooting, the drivers are disabled and device manager says (Code 43)
I'm using this as a second videocard though, so if it doesn't work at all, i don't mind going back to NVidia
EDIT: OK, the drivers doesn't even work with Vista! It's minimum requirement is Windows 7.. But why does it say that it supports Vista on the site?
It's so sad seeing Windows Vista dying like this, it was my fav OS since day one.