Do I Need More Punch?

After summer I was planning on getting a new graphics card, or two, but I'm not sure what to go for and I'm looking for some advice/first hand experience. My most played games are Battlefield 3 and Arma 2 (When Arma 3 is fully released that will be on the list probably). They're the only games I play seriously... everything else I play every now and then for some fun but I generally play one of those games every day.

I can't decide whether to get two HD7870's in XFire or whether to just get a HD7970. I know everyone says that if you can get one card instead of two you should but two 7870's gives more performance on BF3. I've read that some people can get XFire to work on Arma 2 and I've heard some can't. I'd sit down for hours, days if need be, to get it to work on Arma 2 if there's a possiblity it would work. But what do you think?

I've heard of people getting 'CPU Bottlencking'... Think I'd have that problem? I've currently got an FX6100 sitting at it's stock values. Am I going to need to OC this puppy or what?

Go for a single 7970. It will be more than enough to max out both of those games.

I would say get a single 7970 or 7950 and get a fx 8350 because arma is a very cpu dependent game and that mostly dictates your fps for what ever reason lol... good exsample is I have an i5 3570k and my freind has one too both at 4.3ghz and I have a single 6870 and he has 2 7970's in CF and we get the same fps lol. But when I comes to bf3 he gets triple my frame rate soo keep that in mind.

Will get a 7970 then I guess. Cheers for the advice guys. Much appreciated!