|It would help the discussion if you'd have listed your system specs. If your questions are in regards to a system with a P4 2.8GHz & only 512MB RAM, an extremely high end card like the GTX280 would be a waste. The P4 is a highly inefficient CPU & 512MB RAM isn't enough memory for decent gaming or CAD work...you should have at least 2GB RAM. And keep the video card choice in tune with the rest of your system specs.|
Another important consideration when selecting a card is the power supply. High end cards are power hungry & can draw up to 200W or more. The power supply MUST be capable of handling the load or it will need to be replaced/upgraded.
As for the video card, the nVidia Quadro series is specifically designed for CAD/workstations. The difference bewteen a workstation card & gaming card is not so much the hardware design as it is the software. Many Quadro cards use the exact same GPU as GeForce cards...the differences are in the BIOS/firmware & the drivers. In some cases it's possible to flash the firmware & "transform" a GeForce into a Quadro, or vice versa.
BTW, ATI's counter to the Quadro is the FireGL series.