I need you guys input on what to choose gpu set up for me,i'm lost a lilttle bit.I already have the xfx hd 4850 1 gb .What would be a better choice.......crossfire my 4850 or get 1 single card like bfg 260 gtx maxcore 55?...thanks guys.Also is it ok to crossfire a 4850 to 4870? (the same manufacturer )