choosing a graphics card for 3d work

[AlbertK]

Our situation: we use AutoCAD for 3d model creation and conceptual renders. Models can sometimes get fairly large - 5-10MB. At that size we experience very slow real-time manipulation - orbit view pauses or goes blank to regen after every small move, or just hangs. Textural renders can take a LONG time with one or two lights, and just hang with anything more. We figured a graphics card would help - got a Radeon 9200, (128MB DRAM) and it made virtually no difference. System: Sony Vaio, P4 2.4GH, 512MB RAM, (originally shared with integrated SiS graphics chip), AGP, 80G hard drive.

Looks like there's more to better performance than a card with sizeable memory. Questions:
1. I've read that real-time performance is handled by the graphics card but textural rendering still by system RAM. Is that true? If so is there anything besides more RAM that would speed up textural renders?
2. Why didn't the Radeon card make a difference? (Yes, graphics acceleration set to hardware in ACAD, wopengl8.hdi driver) The Radeon card supports Open GL but I didn't find a heidi driver in any newly installed folders. ACAD offers the wopengl8 as the only choice, even after installing Radeon card. Are we overlooking something?
3. I see "workstation" graphics cards like 3dlabs Wildcat or ATI FireGL that appear optimized for CAD applications. How do "workstation" level cards differ from consumer or gamer cards like that Radeon 9200?

 

[RiBeneke]

I have the following experience
Structural steel model where .dwg file size is 15 to 20 MB. Shaded not rendered, rotated using orbit. Acad 2002, WIn 2000, 1GHz Athlon, 256 MB RAM, Nvidia GForce 2mx 64 MB graphics. Initial response time less than 0.5 sec when orbiting. Slows down after the system RAM is full and Win pages to disk file.
It may be that your limitation is elsewhere in your system, such as bus or CPU speed or RAM.