I'm building my first PC, and buying my parts exclusively through Newegg, and I'm finding a set of 4 gig ram (2 x2GB) is cheaper then a set of 8 gig ram (4 x 2GB). the 4 gig set runs for $50 and the 8 gig set is $120 from the same manufacture and same thing (DDR2 800). Why is that? Am I all right ordering 2 sets of the 4 gig?