Depends what you play, but on both Fallout3 and Farcry2, both new games, the GTX2xx are faster than not only the 4870, but the X2 as well. Pricing for the GTX260 and HD4870 1GB are the same too..
And no (less) stupid software issues..
What a myth, they are not faster.. a GTX 260 SLI is roughly equivalent in power to HD 4870 X2, it depends on the games. Just look at
something like this. Obviously when buying a new card you should only be looking at 2560x1600 benchmarks (almost as many pixels as 3840x1024), 1920x1200 or lower is pointless to those of us using Th2go.
Just so its clear that I'm not an ATI fanboy, I had an SLI 8800GTS 640MB up till a few months ago for 2 years (before that a GeForce 6800 GTX). When I upgrade every few years recently I've tended to do it soon after the new generation of video cards comes out (so that I can maximize my gaming experience for as long as possible).
Here's the deal.. the GTX 260 cost $400, the GTX 280 cost $650 at release date. You must admit these prices are ridiculous compared to the $550 the HD 4870 X2 debuted at.
Furthermore the HD 4850 and HD 4870 (for those folks not yet hooked on TH2Go) cost somewhere in the neighborhood of $200-$300 (don't remember exact details since I don't care, HD 4870 CF wasn't ever on my list since it only had 2x512MB=1GB total).
ATI came back with a vengeance, they had the best bang for the buck.. even the HD 4870 X2 was much cheaper than the GTX 280 which could barely keep up without being in SLI.
It is only after ATI gave Nvidia's asses a kicking that Nvidia prices took a deep dive, the GTX 260 is now $200 on newegg and the GTX 280 is a mere $380. That's almost 50% price cuts for both video cards.
So of course with that many price cuts it can now be competitive (just 4 months later) with the HD 4870 X2 which has only gone down to $490 after debuting at $550.
Finally, I don't have a clue as to what software issues you're talking about.. but after I switched to ATI I was finally able to use multiple monitors at the same time without having to turn off SLI first (a feature Nvidia has been promising for what feels like years now).
If Nvidia comes out with something competitive again in the next year, then great, I'll buy it.. but these things tend to go in cycles. Usually it takes 2-3 generations for the other company to produce the superior and cheaper cards, and right now ATI has just regained its mojo.
I extend my sincerest regrets to those who heavily overpaid by buying GTX 2xx near their original releases.