Will upgrade to mac pro 2010 give huge improvement from mac pro 2006?

Question

I asked in an earlier post but may not have been clear. Basically, if I upgrade to a new mac pro 2010 quad core 2.8 GHz (12GB ram) will it give me a huge improvement from a mac pro 2006 2.0GHz (with 5GB Ram) and thus reduce the need to render and the time it takes to render? My thoughts are that it will because the graphics card is much more powerful and has more memory and hence any FXplug effects will have better RT playback. Is this a correct assumption?
Or is this too difficult to quantify. Is it simply "You will see an improvement but..."
I mainly edit 1080 25p Pro Res.
Thanks

Answer 1

Further test has astounded me. I installed my copy of Premiere Pro CS4 on the core i3 iMac. I don't use it on my Mac Pro. I only bought it for Encore CS4 (I had an old copy of Premiere from Windows that I used to upgrade).
I copied an avchd card to the iMac desktop. I opened the media in Premiere Pro cs4 and played it back at Highest Quality: it was smooth as butter even with transitions. There were 47 minutes of footage that I added to the timeline and exported out as AIC 1080 50i. This took 2 hours 20 minutes!
I know that this is far from the ideal: ie editing source files from desktop and rendering to the desktop on the system drive (something I would not normally do, but I did not have an FW800 external drive available). I don't like PPro to edit with and was using to compare to my Mac Pro.
The same clips card were on my internal raid 0 on my Mac Pro. I loaded them onto the timeline in Premiere Pro and it struggled at preview quality and the render to an external esata drive was showing in excess of 15 hours!
I am amazed. But this raises questions for me too. The core i3 is a 3.06 GHz cpu (hyperthreading but no turbo boost) and shows as four cores (two real, two virtual) in activity monitor. They were at 310% when playing back the avchd files. If I get the 2.8GHz Mac Pro there will be eight cores and turbo boost. Will this be faster than the core i3 in playing back footage and much faster in rendering? Or does the higher clock speed of the i3 mean that for editing it is better but will lose out to the Nehalem Xeon when rendering?
Translating these finding to an FCP context, might this mean that a rewrap of the avchd to h.264 for editing in FCP is possible? In some cases this might be preferable to transcoding.
I cannot get over how much better the core i3 performance is over the Woodcrest Xeons. This makes me wonder if the Nehalem Xeons are as good if not better?