can any one explai how raphic cards work 1 HOW does graphic card work? 2 what does it increases? 3 why are all these so costly ? 4 what does it mean by 128 mb and 64 mb ram of graphic card? 5 Is both the ram of o.S and graphic card same ? 6 some 128mb cards are cheap and some 128mb are expensive why whats the diffrence?