Workstation Graphics Card

Hello everybody. I will be purchasing and building a new computer for work for rendering 3D graphics with lightwave v9.6. i already know all of the parts that i will be getting for the comp, but am stuck on the graphics card. i have been searching the internet tirelessly with no luck as to whether or not workstation graphics cards such as the nvidia quadro series actually speeds up render times in 3D applications such as lightwave, Maya, 3ds etc. so far i have seen that it helps with large files pre-rendering using their open GL drivers, which makes sense, but i always figured you would pay $500+ for a decrease in rendering times. so my question is if i buy a workstation graphics card, whether it be ati or nvidia, will the card actually improve rendering times, or will it just be smoother while i am building the scene in the program?

thanks for all the help in advance.

k so i already have a nvidia 9600 gt 512mb, would there be any reason to upgrade to http://www.newegg.com/Product/Prod [...] 6814133272 and if so, would this help render times or would it only be for when im working on the model in lightwave?