Thread is getting derailed into heat and case discussion, as per usual. Yes video cards are hot, we know this. The room with my main gaming rig is quite big and we have central air. When I game I notice the temperature going up around me and literally feel warmer, and my cards only load out at 75.
The question was if the 470 is a better buy than a 5850.
Per Newegg:
470 $350
http://www.newegg.com/Product/Produc...-157-_-Product
5850 $290
http://www.newegg.com/Product/Produc...-330-_-Product
Some benches, using 1920x1200 as 2560x1600 neither card can handle on it's own :
As I said before, the 5850 is far and away the better buy if you bought it 9 months ago because you could of had this performance for the past nine months, and per benches, 5850=470. The 470 has a tiny lead, one you probably would not notice in actual use.
That said if you are buying today you need to decide if you see $60 more value in a 470, which does run hotter and louder if you care about that stuff, personally I don't care about power consumption, just performance.
The thing to remember is ATI's new cards are coming in September, and going on the current trend, you get more performance and value out of an ATI card. Per the example of the 5850 vs 470, 5850 offers the same performance and has done so for 9 months now, and cheaper. 470 has offered this same performance for only 1 and a half months, at a higher cost and the 470/480 will be trumped when ATI's new cards drop.
Currently ATI is ahead of the game, if they can maintain this lead and keep releasing cards that perform well and improve significantly on the past release, a la 48XX to 58XX, you will get more performance and value going with one of their cards buying them at release date.
If you haaaave to buy now, then this is not a consideration for you, just if you think the 470 performs $60 better than a 5850, going on benches, you'd be hard pressed to see any difference in most games. But maybe you could find something appealing about NV's feature set over ATI, if you like PhysX over something like Eyefinity.