Hd5670 1gb vshd5670 512mb

the manufacturer gets to charge you more for the card, other then that there is no difference in performance since the card is too slow to utilize more then 512mb

Indeed. Only get the 1gb version if it is the same price, or maybe if you plan on crossfiring, but that isn't the card I would be looking at for future crossfiring anyway.

Yah....1gb makes no difference..