I have some doubt about using single Graphic card and SLI. I want to know using single graphic card is good or using combination of card in SLI is better. Right now I have Asus SLI motherboard and I require updating my graphic card. I have one fix budget of around $400. I want to know that will it be better using single good graphic card or to use two normal card with SLI. Also provide me some suggestion about one good card or about two cards. Normally I prefer nvidia cards. And I am also confused between x2 PNY GTS250 but 1GB cards and Asus GTX275. I am waiting for your suggestion.