For Metro, disable both Tesselation and Depth of Field effects in the advanced dx11 settings, the DoF setting actively REDUCES IQ, and most people find the game better with it off, it kills performance and is completely awful anyway. Many games use pointless effects badly and kill performance doing so, but because its used as a "max settings" type option some people won't accept its worse.
Likewise, tesselation makes almsot zero difference, you quite literally need to pause the game and zoom in to see 90% of the difference tesselation makes in the game, its generally the very edge of coat sleeves, and the odd helmet and the difference is marginal.
A 480gtx, or a 5870 will drop from 60fps average with 25-30fps mins, to about 30fps average and 15fps min if you enable both settings, at 1920x1200 that is. Basically the two settings make the game unplayable in max details with any setup under a 480sli/5870xfire setup, and all for worse visuals.
Stalker you seem to have fixed, Metro was seemingly working as intended, disable those two settings and it will run absolutely great on a 5870 at any res.
The next thing to upgrade is to go to 4gb memory, more memory ALWAYS trumps faster memory, if you run out of memory your computer and games will slow down a lot. Res will have a large effect on how much memory you need though, dramatically so.