Rendering 5D2 video Premiere CS5 - GPU needed?

Getting a new PC, 64 bit for Premiere CS5.

Is an expensive GPU (£700 / $1,000+) absolutely necessary for the stuff I do (editorial footage 5D2-> mpg2 HD from a simple no layer edit)?

Will an NVIDIA Quadro for GPU acceleration make a difference to rendering times ?

The marketing material is vague. Sure it will allow smooth playback while editing but that has not been much of an issue with current setup (CS4 / DELL 540 4 processor no specialist graphics card). Once rendering starts all 4 x CPUs go to 100% and stay there for the duration, effectively precluding simulateous editing and rendering.

Will it help with rendering times - the current bottleneck?

Thanks for any help.