Have you checked temps? Have you checked to make sure that the games you are playing dont already have issues with the drivers for the card you have? What other devices do you have? Are you sure that there are no reported problems with anything you run and any 64 Bit OS?
There is no reason why you should be getting crashes out of nowhere on 2 different OS's like this. So there has to be an underlying factor. Bad 64 Bit drivers, system running to hot, faulty mobo or RAM. Something has to be causing it.
What was teh BSoD? Just saying there was one tells us nothing. There are almost 200 BSoD's out there. All have different factors that cause it. Do you have the dump files?