Quattro cards are intended for people who use 3D modeling, you will see no benifit for general use or video editing over normal Geforce cards.
Suggesting a 200series nvidia card is retarded, they are high end gaming cards and totally pointless for what the OP wants.
Also CUDA runs on Nvidia Geforce Cards not just on Quattros.
The NVIDIA Quadro FX 580 is essentially a slightly altered 9500GT for twice the cost.
You said that is no gain using Nvidia Quadro Card for editing videos.
I'm going to build my new computer and it will be:
Seventeam ST550-PAM (550watts)
Video Graphics Nvidia Quadro FX570(580), or
XfX Geforce 260/216.
What you thing about it and which Grafhics card you suggest to work with Premiere C4 and Sony Vegas 8.0.