thats how it always is, they too lazy to optimize the older cards for newer games, thats the benefit of buying the latest generation mid-range card , it will get faster and faster (drivers), while if you buy that last generation card, it will get more and more problems, and even loose a little performance over time (drivers) .
When i first got my 8500 , the stock drivers were speedy as hell , played all the games with no problems , 15 driver versions later, i haver 3-4 major and annoying bugs in the same games that played great, artifacts sometimes for no reason....