you will be playing the game at high performance with these setting, i dont know how much you can shell on that machine, but you are upgrading to a 1 year old setting. If you want the system to last you longer, shell a bit more and get 2gig or ram and get the videocard 1 level higher i dont know which ones they are as i havent upgraded in almost 2 year and i am myself using an ati9800pro.
With that card and 1 gig of ram, and a 2.4 p4, i run at high performance pretty easily and balanced when not too many people around and i solo.
As for the game being optimized for Nvidia its just some commercial ********* the game isnt optimized for nvidia more than its optimized for dell system hehe.
Btw never had a single problem with ati card, just too bad the new one cost a god damn lot of $.
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Brynioch
70 Priest
Khaz Modan
"Fear comes with the possibility of death, calm shepperds its certainty"