Hmmm My performance in Vista was lower than in XP with the same settings, same res, same drivers (169.01). Not too much lower, but still lower. And personally after runing Crysis on Ultra High (DX10 mode) I was unimpressed with the additional graphics. They were minimal at best& I would not recommend Upgrading to Vista just for DX10 to anyone.
Jon, just out of curiosity, where are you getting the info on DX10 performing better?