I have a 2007ish Mac Pro with two 2.66GHz Xeons. I've boosted the memory to 8GB, upgraded the video card to an (aging) X1900 and installed a SSD as the boot drive. Of all the computers I've ever owned this one has the longest lifespan. I'm thinking though of upgrading to the current 2.8GHz Nehalem versions. Ignoring the video aspect as well as the fact that the Mac Pro is due for a refresh, how much of a speed boost will I realistically see? I can't seem to find any benchmarks.