The 660m is a 650m with GDDR5 vs the DDR3 of the 660m. The card itself is so weak that the GDDR5 results in a 3% increase in performance, that's barely outside of the margin of error. I'm not sure what you're looking at, but if it's in the $750+ range just spend a bit more for a 765m. It will be a massive improvement over the 650/660/750(a 660m with slightly higher clocks)m.
Every time I try to go where I really wanna be it's already where I am, 'cuz I'm already there XBL, PSN, Steam, Origin, BSN, GFAQs, MC: PhilOnDez