http://www.gpureview.com/show_cards.php?card1=350&card2=55
They are a bit better. However, I'm sure the x850 gets much more hot and the fan's much louder than the x1600. Also, I'm sure it requires more power. That's the main reason I went with the 7600 rather than one of those x850s.
i've been told these are considerably better than x1600 cards
http://www.newegg.com/Product/Product.asp?Item=N82E16814102688
Nowould i notice a bigger difference with the same card at 512mb?
Most likely not, since that card isnt powerful enough to run games that require 512MB of VRAM.i plan on getting the 512 one...dunno if you'll see a difference between the 2 though