which of these is good for gaming and graphics rendering ?? NVIDIA® GeForce® GT 640 1GB GDDR5 1GB AMD Radeon(TM) HD 7570 (DVI, HDMI, VGA: via dongle)
I'd have to say the ATI. Nvidia seem to be focusing on scientific applications rather than gaming these days, and their recent cards have incredible specs on paper but don't seem to deliver in games.
^Screaming AMD fan. I checked both of your cards you were looking at and, well, it's kind of hard. With low-range price cards, it doesn't matter very much. Both have limited performance. Here is a benchmark about both cards : http://www.anandtech.com/bench/Product/612?vs=614# According to that benchmark, it gives indeed the upper hand to the AMD card. But, at the end, it all depends of what you do with it and what budget you have to spend on the matter.
another clue is to look at the two major manufacturers of gaming graphics cards: XFX abandoned nvidia and went ATI only, BFG did not and went bust.
