Moved over to a ATI 5870 vapor-x from a 8800GTS and whilst it has allowed me to max games out at 1920 x 1080 in terms of how games look, not been all that blown away. but it is quick, and only Metro 2033 give it something to do... Oh and F1 2010 but that game has some right shoddy optimisation since the recent patch codemasters released - nice one.!!
Been very impressed mind with HL2 and cinemod 10.90 fully maxed out, and I was very impressed with Metro 2033 fully maxed but DOF and tessellation killed it.
TBH can't see me changing GPU for quite some time, every single game i've thrown at it has done more then enough FPS even with v sync on to make me think - why buy anything more powerful at the moment??