I just received a 450 in replacement for the 8800GTS I've been running for the last... years, I dunno how long. I didn't need to upgrade but since the 8800 cooked and I wasn't sure I'd get warranty replacement I bought an AMD 6870 and that's what I'm running in my main. I also happen to have a 460 in my HTPC which is used for Lego games (Batman, Harry Potter, PotC, Indy 1&2, and both SW) as well as Portal 1&2, and some GH3. Crazy kids.... Mostly all I've been playing is Borderlands.
My main is driving 1900x1200, the HTPC 1920x1080. I've demo'd recent FPS (Rage, Metro, that one where the city is a boat, others I can't remember) on my 8800 and had no issue with quality or frame rates. The games themselves sucked. What I have noticed on changing to the 6870 were certain irritating glitches w/ graphics all went away. Now the question is was it the driver switch to AMD from NV or what? I haven't bothered testing on the HTPC because I don't play these games on it (not good for young eyes!) and I can't try it now since the PSU fried. Don't try driving a real rig w/ a 6year old 330w PSU. It actually survived that load for 10 months, SeaSonic makes good stuff.
So anyhow... don't overdo it, these days there's really not that much driving hi-end GPU purchases other than ePeen and some weird requirement to hit certain numeric goals. I have NO IDEA what my frame rates are, but I come from buying top end stuff for my PC because I could into not needing to because I'm no longer seeing the gains.