Aqua-Soft Forumsso what about this Ati radeon X1600 128MB ??? ... should wait another 5 weeks for them to ship me 256MB one? ... i do not play games at all but my brother says i should get such one for ocasional gaming when friends come round ... but i see where hes headin 
... gues hell want to borrow me mac sometimes to play his games! ... well ... perhaps ill allow him to from time to time ... so then ... what you think? ... and what is your experience with the 128 MB one? ... is it good enough to play games in high resolution?
gaming and iMac 20" graphics
I went with 128... x1600 is a mid-range card and 256 will be noticable only if you have more than one screen. Games that will require 256 as a min to play will require more than x1600 chip can do anyway.
wow ... y solved me dilema thnx so much
My iMac has the x1600 256MB. I play GTA San Andreas and it's very smooth during game play. Not much I can tell you about the 128MB one.
Me MacBook Pro has the X1600 @ 256MB as well. I run Counter-Strike: Source at (almost) full settings and it's pretty smooth.
I would say general concensus would be if you plan on playing games then the more memory you can segregate for your Graphics is better.
Just remember the only down side of the iMacs is lack of upgradeable parts... so If your thinking of this as a gaming machine... you might want to think twice.
Unbeliever is correct, the 256MB version is going to have minimal to no noticable effect on games. More RAM on the video cards these days doesn't do a whole lot like it used to. Sadly, Apple seems to be trying to take advantage of unsuspecting users by offering it as an upgrade.
A sensible upgrade involves a different GPU not just tacking on some more RAM and charging an extra $75. I think the Mac Pro is the only one that allows you to really upgrade the graphics.
I have the 128MB in my iMac and all the games were very smooth (GTA San Andreas, Company Of Heroes, NFS Carbon, NBA Live 2007...), except for Scarface. It was playable though.