they both have similiar features. both are 128bit bus. both have 1GB vram. the 650 has slightly faster memory clocks. they both a similiar clocked processors (give or take 20mhz). the 7770 will net you more fps on average over the 650. http://www.anandtech.com/bench/Product/536?vs=681darksusperia

Would it max any of those games I've mentioned?

get this instead http://www.amazon.co.uk/Asus-DirectCU-CrossFireX-Technology-Eyefinity/dp/B007RS49EG/ref=sr_1_5?s=computers&ie=UTF8&qid=1360548793&sr=1-5darksusperia

Can you tell me a bit more about why its better?

I am looking to replace my GPU as mine is weak.

My rig:

Mobo: M5A78L-M/USB3

CPU: AMD FX-4100 Quadcore (Bulldozer)

RAM: 8GB

GPU: Nvidia GeForce GT 610 2GB

I'm thinking of a: GTX 610 (Maybe this: http://www.amazon.co.uk/Asus-GeForce-DirectCU-Express-DirectX/dp/B0098VKIQI/ref=sr_1_1?ie=UTF8&qid=1360548150&sr=8-1)

I'm getting SimCity 5 and I also play Fallout New Vegas and GTAIV.

Is this a suitable card and is it budget friendly? I really don't want to exceed £100! Also it doesn't have to be THAT particular card. 

On a side note: Will it run blurays?