This is still the well known ATi HD version problem (nVidia has it too). It hasn't got anything to do with your card, it's just the drivers which cause problems with Vista, or Vista causing problems with the drivers.
The thing is that Vista is saying ATi and nVidia are the ones who make faulty drivers.
While ATi and nVidia are telling everyone that it's Vista which doesn't support their cards. And this has been going on for 1,5 year now.