opengl is very fast. its done partially in hardware . Its very fast .

I normally dont work in texture preview mode , because opengl is very hardware and driver dependant. I run a render to check textures and then  run the final render at full size and with all the bells and whistles turned on .

For me a video card is near the bottom of the list for upgrades. I would add system memory because that will give a nice boost to rendering . I can say a nvidia 6200 gt card works nicely with poser, but mainly for the opengl. I had to upgrade to get another application working .