Thank you for all your answers so far
I have a Corsair 550W Power Supply, so power shouldn't be an issue. I think I'm going to buy the 7770.
Gigabyte nVidia GeForce GTX650, 1GB, GDDR5, DVI, HDMI, PCI-E
Sapphire AMD Radeon HD7770 Edition OC, 1024MB, GDDR5, 128bit, DVI, HDMI, PCI-E
Im leaning to AMD but they are evenin performance. Your choice.http://www.tomshardware.co.uk/forum/379769-33-7770
Good luck with your studies !