Re: Nvidia 260 GTX ot ATI HD 4870
i would take one of those pre-overclocked models like the bfg gtx 260 ocx or the xfx gtx 260 xxx, or evga gtx 260 ftw over the 4870, but not the reference gtx 260.
here i got the xxx one for $310, which is about $0-$20 more than the 4870's you can find, but it came with cod 4 (a $50 game i wanted), so it was a no-brainer for me what to get.
in your case, it seems that the non overclocked model costs more than a 4870, so, in this case, I, a gtx 260 owner, say you should get a 4870. unless you do folding@home (where the gtx 260 is like 3x as fast as a 4870).
DFI P965-S...core 2 quad Q6600@ 3.2ghz...4gb ddr2 @ 800mhz cas 4...xfx gtx 260...silverstone op650...thermaltake xaser 3 case