2.8, 3.2 or 2.26?

Hello, first post here. I've been lurking around this site and others for a couple of weeks and reading as much as I can. I am about to buy a new Mac Pro mainly to be used for FCS2 and Photoshop CS4. I see that some people prefer a higher Ghz "2008" processor over a 2.26 Nehalem, but others say to go for the newer architecture. I plan to edit HDV from a Canon HV30 and would like the ability to output to DVD (or higher quality if possible).

Given these 3 system options and pricing (all new systems), which would you recommend for my needs? I know I should buy the "best system I can afford", but I'm wondering if the lower priced systems would be better if I took the price difference and upgraded the systems (ram, video card, or hard drive, etc...)

2.8 - 8 core "Early 2008" (2 x 2.8ghz, 2GB ram, 320GB hd, 2600XT) - $650 less than 2.26

3.2 - 8 core "Early 2008" (2 x 3.2ghz, 2GB ram, 500Gb hd, 8800GT) - $200 less than 2.26

2.26 - 8 core Nehalem (2 x 2.26ghz, 6GB ram, 640GB hd, 120XT)

Should I get the 2.8 and $650 for upgrades, the 3.2 and $200 for upgrades, or just stick with the new 2.26? If you recommend the older systems, which upgrades would you recommend for the money allotted?

I realize that with any of these systems, I will need to get additional items (hard drives, ram, etc...), but I am looking for a base system right now.
Thanks,
Bill