Video Editing Workstation Bottlenecks, Best Choices

[downplay]

I'm spec'ing out a couple of video editing workstations. Our videos are simple, 2D,
and only use functions like slow-mo and crossfade. We crank them out one after
another fast as possible, so we'd prefer not to wait on the machines much, if at all.

I am looking at a workstation class system and mother board:

16 or 32 GB RAM ECC 1600 RAM
AMD FirePro W7000 graphics with 4GB dedicated RAM
SSD
4 or 6 core Xeon at 3.6 or 3.2 respectively
Win7 and Sony Vegas Pro 11 or 12

What are the bottlenecks, where would you spend more or less?
Will the 4 core processor be fast enough or should we pop for the
6? Is that class of video card overkill? Is the RAM overkill?

The W7000 has a built in H.264 engine and plenty of onboard RAM. We will use
MP4 format so it is also why I chose that card.

I don't want to waste money or good hardware!

 

[tiny voices]

There are no bottlenecks.
16gb of RAM will be plenty. 8gb would work too.
You really don't need that powerful of a video card for what you are doing. A lower end gaming GPU for cheap would even do it just fine.
You don't need a 6 core CPU. A plain old 15 would likely be fine.