Well if a 470 or a 6870 is out of price range and you want more performance than a 6850 or a gtx460 then you should go with a 5850.I think it's right in between your budget.The 5850's are selling for cheap now ever since the new 68xx series came out.
Get a 6870 if you can,they are very good cards and give even better performance when it comes to crossfiring.I currently own a XFX6870 and it's great.
The GTX460 O.C. is worse than a 5850.
Depnding on your resoultion you should have no problem maxing out COD series games.But if your playing BFBC2 or Arma 2 your gonna need x2 6870's to max it out.You can still play them on high settings but you can't use the eye candy(AA AF etc.)
I can't tell if that version is or is not.
Why buy from amazon anyway?why not newegg?
I also game on a 20"1600x900.I manage 50+FPS in BFBC2 with no AA and no AF.I'm sure you can mange playable FPS with everything maxed out but i like to play as close as possible to 60FPS.Like i said before theirs absolutely no problem running the COD series games.I get around 90+FPS.
With your i7 i'm sure you can crank out another 5-10FPS per game.
if the 6870 is in your price range, definitely get it over the 5850. Better performance for new games. in some games the gtx460 is faster than the 5850 but the 6870 will be faster than all those cards in nearly all circumstances.
well for video editing the 460 will be better, even if it isnt oc'ed. This is because video editing also has a lot to do with your cpu and the gtx 460 has cuda technology. So it's up to you to decide which is more important, gaming or video editing? I'd prefer the 460 because it has very good framerates at 1920x1080 and (the usefullness of this has been debated) it has physx technology, great sli scaling and ofcourse cuda, which, for lack of a better phrase enables the graphics card to "help" the cpu in certain cuda compatible programs such as video editing. For me the great, yet slightly lower framerates in games are an acceptible trade-off. But in the end put all the pros of each card on a scale and see which way it leans man. Good luck with your decision.