Telinar, I use AutoCAD a ton... At work, I use it for architectural drafting (both 2D and 3D). At school, I use it for technical drafting and 3D part modeling, and at home, I use it for both. All three of my workstations use different graphics cards, and, to tell you the truth, I can't tell the difference between any of them. I think that a fast main processor with lots of RAM is far more important than the graphics card for AutoCAD work, simply because AutoCAD's HEIDI display driver is plenty fast with a normal graphics card. Your GeForce3 Ti200 should be plenty for a graphics card. And it looks like you have more than enough RAM, and a fast processor to boot.
What kind of work do you do in AutoCAD? 2D or 3D? And is your display performance holding you back? My workstations at school and at work both use integrated graphics and are running Pentium III processors. (My new computer for college that I use at home is a little different story...check the link on my signature )
I would say, unless you have money to burn, or you are working with models/scenes that have HUGE polygon counts (200,000+), then you won't notice a difference with an expensive workstation graphics card.
-Scott Fehringer
-Roseburg High School Drafting
-4th Place Winner---Technical Drafting at the National SkillsUSA/VICA Championship