The pro version is just a higher clocked version of the GTS card. Most good GTS cards can be overclocked well. I can get my Elsa Gladiac GTS to run at 220mhz core and 370mhz memory, compared to the reference default of 200mhz/333mhz. The scores usually improve 10-20% with the overclock, so unless you found a PRO version for only $20-$35 more than get it, otherwise buy a good brand GTS version. Also, 64mb version are only going to make a difference if you play games in 1280x1024, or 1600x1200, otherwise don't waste your money for the other 32mb, again unless the money difference in small.