Succinctly put elmano.
ImperfectCircle, The 1600 is definitely geared towards augmenting a hardcore media box more than a gaming rig. Also, very few games make use of 512mb framebuffers just yet. I daresay the concept is only ideal for dual-card buyers interested in future-proofing their rigs.
On another note, if you're not locked into a choice between those two cards, might I suggest the X800gto with its unlockable shader pipes? It may just be your ticket to a cheaper x800xt if cooling permits. :roll: