Ok i know a lot of guys don't use this so if u can relate with maya u can use it as reference.
The Cards I'm considering are: gtx 275 and hd4890
Now, yes they'll be used for gaming and from the recent graphics card charts the 4890 wins there.
I also need to render in autocad and autodesk Inventor, i've heard sum random stuff about ATi drivers not being good for 3d rendering in these software environs, which is what lead to the consideration of the gtx 275.
Now, i also know that some ppl are gonna recommend flashing the cards.... just no, i cant afford to mess with the card too much...
Others may recommend quadros and firepros...i dont have that type of funding this is my personal build and im struggling along in university in Jamaica, and i have to worry about port taxes and such.
So plz throw in ur 2 cents and lets c which direction i should head in.
I think either card would be fine for CAD. I use Autodesk Inventor on my weak X1400 and it seems to work great. Now, that isn't high res or anything, but I think that means the ATI drivers are at least decent. I'd recommend not worrying about the CAD aspect and going with the better gamer as they both should CAD well.