Best Power Graphics Card for Basic 2D Video Editing?

[downplay]

We are trying to spec out a blazing fast video editing workstation. Our vids
only require basic cross-disolve and slow-motion. We have a pretty good
budget but at the same time I don't want to waste money.

I'm finding the choice of which is best a bit daunting.

Would this type of processing be better for one bad-to the bone Graphics
card or two lesser cards?

Which would you choose:

AMD FirePro v7900 2GB
AMD FirePro w7000 4GB

NVIDIA NVS 300 or 310 512MB

NVIDIA Quadro 410 512 MB
NVIDIA Quadro 510 2GB
NVIDIA Quadro 600 1GB
NVIDIA Quadro 2000 1GB
NVIDIA Quadro 4000 2GB
NVIDIA Quadro K5000 4GB

 

[downplay]

If it helps we will run Sony Vegas Pro 11 or 12 on a very fast machine with 1600 ECC RAM, Six core Xeon, SSD, etc.

 

[ARICH5]

id choose the higher vram solution at 4gb