I would help, but I'm an Intel fan. Sorry. ;__;
EDIT: What about this? It may be a tad over budget. o.o
EDIT: Let me find it somewhere else. Newegg doesn't ship internationally.
EDIT: Here. I'm not a big fan of amazon though (I really have no idea why).

AMD Phenom(tm) II X6 1075T 3.00 GHz.I'm using it for 1 year and its great.I'd recommend 1100T Black Edt. but it is too hard to find.Anyway, 1075T is great and should do the work for you.

I just realised that 1075T is too damn old.A lot cheaper and a lot better CPU's released since I bought one -_-

AMD FX-8120 Zambezi 3.1GHz Socket AM3+ 125W Eight-Core Desktop Processor <--- this looks good if you're in for bulldozer series.It needs AM3+ socket though, I have AM3.I'd buy this if I could.

What is your current CPU?

FX 8320 or 8350 (this one is more expensive but worth it).
I currently have a FX-4100 which is okay but I feel like upgrading later on. I will be getting 8320 most likely.

the FX 8320 cost around 140-150€, get this. Or if you like one with integrated graphics, choose the A10-6800K for like 140€, but the first is more better. Running Battlefield 3 depends on the Graphics Card, even the integrated graphics processors (APU for AMD), can run Battlefield 3 smoothly but not in 1080p.

These days, most 3D software handles multiple cores pretty well, so the more the merrier, which is why I would recommend the FX 8320 to fir your price range, though the 8350 will give you a little more bang for your buck. The extra 500mhz right out of the box per core will really help with any single core reliant operations you need to do, but it's a bit out of your budget. Either one will handle everything you throw at it, and you won't need to upgrade for several years. Unless you have a garbage GPU, bf3 will run on ultra easily at 60+ fps, more likely 100+.

Alot of people will say go for the FX CPU's, I say screw that ...
Get an AMD A10-6800K Richland 4.1GHz, even a good FM2 mobo is cheap

This is my build, AMD masterrace included.
Either the CPU I have list or the FX-6200 is best.
http://pcpartpicker.com/p/1ybay

Well, I don't know how much is it in your country/using your currancy, but I'm using AMD since forever, and now I have Phenom II X6 1055T
I think you'll be more than safe with anything between 4 and 8 cores. Do not cofusse with threads. AMD is very good hardware price-wise and is great for both play and work; I do renders myself as a hobby I like to model 3d objects and even a bit of animation. Check what's available to you. Also very important: don't forget about ram, as much as you can buy, no more than 16gb no less than 4 or even 8. VGA only if you want to play. I have Sapphire 7850 2gb and it rocks!

I can run BF3 smoothly (even on 64 player servers) on ultra with an amd phenom ii x4 840T, so anything better than that should be able to run it well.

I don't want to be rude, but I'd buy an i5, because those are better for what you need at this moment, and you don't buy the brand, but the product. If you really want to go for an AMD, I'd buy either an 965be or an 960t, because they are cheap and have good performances; also the am3 motherboards don't cost much + the FX series don't worth the price.

Intel

If you can, get the money and buy the fx 8350. This is the best AMD for playing, and you can up to 5ghz easily if you buy a 990fx motherboard.