I have been searching for newer Mac Pro for quite a while now to replace my 1,1. First, keep in mind I will use the Mac Pro for heavy Lightroom and Photoshop use. I found a 2-2.26 4,1 to buy, for around 1,100. However, I have a Mac Pro that is 2-2.66 already. Should I be going backwards on clock speed? Will I notice improvement in Lightroom?