Ok, don't misunderstand me.

Forget the harddrive for the moment.

With Ati X1900 and 2 TH2G you can run 6 x 800x600 max.
What is with the Nvidea 4500? Can I run 6 x 1024x768 max.

Or can you tell me what is the advantage in using the
NVidea 4500 instead of the ATI1900?

Andre