SLI'd GTS's should be good. Can't wait to see something like that up and running. You will be blown away whatever you end up getting btw.
As for medium settings. It doesn't matter how it looks as long as you're immersed and having fun. Otherwise it's just too hard to have fun whilst being disappointed at the same time.
Company of Heroes and World in Conflict. Go for those two. Takes you away from the FPS side of things for now. Unlucky on the CSS rankings. It does require you to play but then again I just had a better than 5 kill to death ratio after not playing 4 months. You should always pop in for the odd game as you realise that it's fun too.
Crysis multiplayer?. Not tried it yet

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