Well, for starters, the GTX 650's GPU has 384 unified shaders, or stream processors, whereas your GT 610 has 48.
The number of stream processors in the GPU, combined with its clockspeed, is a major determinant of a graphics card's overall performance. Another is memory bandwidth, which is determined by memory bus width and memory speed. Frame buffer size only matters when you run out of memory. KotOR only requires about 420MB at 1080p.
As I said, Nvidia's shader model changed when they switched to DX11 and the Fermi architecture. The individual shaders are less complex and weaker, which is why there are more of them in the newer models. You would need at least a GT 640 to equal or surpass an 8800 GT's peformance.
To get a good deal on an 8800 GT, you'd have to buy one used from a reputable dealer on ebay.
"They should rename the team to the Washington Government Sucks. Put Obama on the helmet. Line the entire walls of the stadium with the actual text of the ACA.
Fix their home team score on the board to the debt clock, they can win every game 17,000,000,000,000 to 24. Losing team gets taxed by the IRS 100%, then droned."