i wanted to get a jumpstart to my pc gaming routine and i was going to buy a new graphics card but the one i want comes in 128 and 256 mb versions. i can get the 128, but id have to save a little more for the 256. when do i really need the extra memory? or will 128 cut it for mid/high end gaming? the card is the ASUS N6600/TD and costs $120/$150 for the 128mb/256mb respectively. the prices are from newegg.