Where did you get those drivers? atikdmag.sys means that there is a problem with your driver.. Try googling that error and see what other people say about it. And, this is a question rather than something I know, but an nforce mobo with ATI GPU? Does that work together?:s ...
you have installed drivers for the card and not the cat control centre? the catalyst control centre (center for our yank friends) controls all of the effects your graphics card is capable of, ie/ image quality, anti-aliasing and anisotropic filtering, thats why your drivers are crashing.