PewPew, i could get this for an extra ?80
Sapphire ATI Radeon HD 6850 1024MB GDDR5 PCI-Express Graphics Card
Thats kind of top budget... The one you suggested was +?250, which is to much...
what do you think to that one?
Okay cheers phobus, It'll be fine for DoD i guess though?
The 6850 will do you fine since you only plan on playing source games. It's more than enough and will allow you to play some other titles down the road too. Just don't expect to max out every game that comes along. You could always crossfire when you need the extra power since the 6850's scale tremendously and will get you performance of about a 5970 or almost 2x5870.

Question.... why is the 6850 worse than the 5870? Shouldn't every 6xxx card beat the 5xxx cards?
If you're actually happy about buying a card for $100 more for ~7% more power, you might have missed the point. Anyways, the 69xx series, which is the 6xxx's top-tier option, is supposed to be rolling out in Q1 2011 and should replace the 58xx line for that price range.
If by Q1 2011, you mean December 13th, then you are correct. Unless there was another delay. *cough* Fermi *cough*