Reddit mentions of Sapphire Radeon Hd7750 Graphics Card (1Gb, Gddr5)

http://www.amazon.co.uk/Sapphire-HD7750-Retail-PCI-E-Graphics/dp/B00761YFPW/ref=zg_bs_430523031_5

I have a much better card than this but If I was on a budget I would start with something like this and then upgrade..... "super mario" thats typical elitist talk - subjectively unless you want to play everything maxxed out all the time then you do not need the latest, or even last years greatest video card. I had a much older card than this until recently and there was almost nothing I couldnt play to some degree.

Germany is pretty expensive for computers.

Amazon UK and Amazon DE have free shipping to germany on some hardware over £25 / EUR25. Just tick the "free super saver delivery" box.

Completed PCs will usually be pretty expensive. I have just started my own company for that, but I'm not completely done setting up shipping arrangements yet, and since I'm situated in Denmark, shipping to Germany is not yet an option.

You could try using Amazon UK and Amazon DE to get a cheap:

Corsair CX or XFX PSU

B75 (Intel) motherboard or FM2 (AMD) motherboard in Micro ATX size. Get from Asus, MSI, AsRock or Gigabyte (the 4 best brands).

Cheap Pentium 2020 (or higher) CPU (Intel) or an Athlon II 760K from Amazon UK (AMD).

Cheap 4GB DDR3 240-pin RAM module. If you have a motherboard with 4 RAM slots, you can also get 2x2GB (which is often cheaper).

Cheap ATX or mATX case (at least the same size as your motherboard) with at least 1 case fan. Something like this: http://www.amazon.co.uk/Sharkoon-VS3-V-Chrome-Optical-Drives/dp/B00B1MU6YQ/ref=sr_1_41?s=computers&ie=UTF8&qid=1377069838&sr=1-41

or the USB2 version:

http://www.amazon.co.uk/Sharkoon-VS3-S-Chrome-Optical-Drives/dp/B00B1MU7WW/ref=sr_1_39?s=computers&ie=UTF8&qid=1377069838&sr=1-39

Or this:

http://www.amazon.co.uk/HEC-Compucase-Cougar-Spike-Micro/dp/B00BP6NHRQ/ref=sr_1_55?s=computers&ie=UTF8&qid=1377069969&sr=1-55

Or perhaps:

http://www.amazon.co.uk/Xigmatek-CCC-AE45TS-U01-Asgard-III-Chassis/dp/B004IKDYBU/ref=sr_1_66?s=computers&ie=UTF8&qid=1377069969&sr=1-66

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Then add a cheap HD7770 (or HD7750 with GDDR5 memory) graphics card:

http://www.amazon.co.uk/Sapphire-HD7750-Retail-PCI-E-Graphics/dp/B00761YFPW/ref=sr_1_1?s=computers&ie=UTF8&qid=1377070099&sr=1-1&keywords=HD7750

http://www.amazon.co.uk/Gigabyte-7770-Graphics-GDDR5-PCI-E/dp/B008FPJ8DC/ref=sr_1_9?s=computers&ie=UTF8&qid=1377070170&sr=1-9&keywords=HD7770

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Go with this 1TB WD Blue HDD:

http://www.amazon.co.uk/Western-Digital-internal-Hard-Drive/dp/B0088PUEPK/ref=sr_1_1?s=computers&ie=UTF8&qid=1377070264&sr=1-1&keywords=1tb+wd+blue

I'm not sure how cheap this is, but it doesn't get much cheaper in Europe, unfortunately. Remember to add OS if you haven't got Windows.

Sorry if i bother you, but i compared my pc to the new one and saw that i can "recycle" it. I think i only need to upgrade my motherboard, graphic card and ram. Do those work well together?

http://www.amazon.de/gp/product/B005504QAA/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=A3JWKAKR8XB7XF

http://www.amazon.de/gp/product/B00761YFPW/ref=ox_sc_act_title_4?ie=UTF8&psc=1&smid=A3JWKAKR8XB7XF

http://www.amazon.de/gp/product/B0037TO5C0/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A3JWKAKR8XB7XF

So here you have link to shop + FPS that this graphics reach in Battlefield @1680x1050 Ultra detal AAx4 AF x16 DX11 but with it's with insane CPU 2600k overclocker to @4,0GHz note that test was in single player I guess.

MSI HD6770 2GB 69 pounds - ~47 FPS
Sapphire HD7750 1GB 87 pounds - ~45 FPS
Gainward GTS450 1GB 72 pounds - ~40 FPS
XFX ATI HD6850 1GB 90 pounds - ~60 FPS

With any of this graphics you will run your League Of Legends on Ultra details on stable 60FPS. Also we need to know power of your PSU follow iCorpsy steps!
Your CPU is quite good since it's has 3 cores so maybe you will be able to play Battlefield 3 on Low detals with ~40-50FPS depends how many players are on server.
I'm owner of ASUS HD6850 and AMD Athlon II X4 640 (almost same as your's but mine have 1 more core (4cores)) and 4GB. I can play Battlefield at average 70FPS
IMO: 6850 > 6770 almost same as 7750 > GTS 450