Mac Pro - Which one configuration?

I don't actually own a Mac Pro, but I would figure that the 2.8ghz octo would be more than enough. In fact, from reading your post, I would bet you could make it on the single quad core 2.8ghz, if not an iMac.

 

In my opinion the benchmark difference between the 2.8 and 3.0 is so minimal it's not worth the extra cash. I would say that cash, if you have it and need to spend it, could be put to better use on ram and hard drive space.
I would even tend to agree that the quad would work but in my opinion buying the quad is almost silly because if you could run on a quad then why bother with the macpro at all? Just get the 24" iMac.

 

Here is another fact that might settle your mind:

The 2.8 Octo is just as fast as the old 3.0 Octo.

Believe me, 8 Cores is plenty of power for the home.

 

As a Mac Pro owner, I must say that regardless of what people say, the quad is a speed demon nonetheless. I edit HD video, make complex 3D models, and program, and the Mac Pro handles all of it with room to spare. Mine is a 2.8 quad with 4 gb of RAM and 2 500 gb hard drives. I would upgrade to octo for speed boosts it the already zippy video exports, but I can find a second heatsink on the market. I would have to say that for what you are doing, the quad would handle it all without breaking a sweat. It is a very great machine, plenty fast for what you say you will be doing.

 

A Mac Pro sounds like overkill for what you want to do but hey it's your coin and there's something to be said for having the meanest computer on your block.

If I might make a suggestion a Macbook Pro + external monitor would be a little cheaper and have more than enough juice to do what you're looking for and give you a little mobility to boot.