Considering purchase of a used Mac Pro. The choices are basically: - Early 2009 Nehalem 4 x 2.66GHz with NVIDIA GeForce GT 120 512MB - Early 2008 4 x 2.8 GHz with NVIDIA GeForce 8800 GT 512 MB What speed difference would you expect to see between the two on CPU and graphics (games, photoshop, lightroom) tasks? What if the latter was an 8 core instead of a 4 core? Where do you see the big boost from the extra 4 cores? Is it noticeable in lightroom/photoshop type tasks or only on really heavy lifting stuff such as 3D rendering and video encoding?