Here are my video settings:
Running a sapphire HD 5770 (
this one for about 10 months now), game looks like sex. I typically run on a bit higher settings (terrain, textures, object details up on high/very high), because I'm happy averaging ~27 FPS, bumped them down to normal today to see what it's like in the ~37 FPS range (also nice, no hugely noticeable differences in attractiveness)
If you look at Tom's Hardware's benchmarks, the 5770 is low on the list, but the 4670 isn't even ON the list (2011 list -
http://www.tomshardware.com/charts/2011 ... ,2674.html ). That review Q2M100 posted above looks like BS, for a few reasons:
1) It doesn't list specific cards on which those benchmarks were tested - apparently they represent all versions of the 5770 and 4670 (more likely they're made up)
2) The two cards are clearly in vastly different price brackets. If they actually performed at similar levels they would cost similar amounts - ATI isn't stupid, they're in the game for the money, and they're not going to underbid themselves.
3) Tom's hardware doesn't even have a review comparing the 2 (at least not one that can be found in 10 minutes of searching). That's because the 2 cards are leagues apart - the 4670 is a budget card, while the 5770 is a low-end enthusiast card.
4) Here's a nice example where HWcompare quotes Tom's Hardware on the speed of the 5770 vs the 4670:

(This is the bench for my 5770)

(This is the claimed bench numbers - you can see the sapphire 5770 actually produces about 84% more FPS than the 4670)
In short, if you want a cheap graphics card buy the 4670. If you want to play arma 2, buy a 5770. The 4670 is garbage, as its price range would indicate.