I have a mac Pro 1,1 with dual core 2.66 processors. I have been looking at upgrading as aside from normal use I do a bit with Vmware, mostly POC stuff for work, so anything thing from 2 Vm's to 2 or more virtualized ESX hosts with 3-5 vms running inside of them. For the POC's the performance of the VM's is not what is being tested so in the past they system has been up to stuff. Lately as things get more complicated I have running tight on RAM and on occasion am taxing the 4 cores. I have been looking at upgrading the ram to 16GB (currently at 9GB) and have also been on the look out for X5355 or x5365 processors to upgrade too. This week I came across a Mac Pro 2008 2.8 Quad core for a good price, less then what 2 x5365 would run me on Ebay. So now I am trying to decide it I should pull the trigger on it. I guess part of what I am looking for is if a 2008 2.8 is going to be better for run heavy VMware loads vs a single CPU 2009 Nehalem Mac Pro? IMO the answer is yes as the 8GB limit is the killer. I look at for the same $ I could get a second system, more RAM for both and maybe an SSD for the primary to boot off of or to use for VM's.