I'm running an MP 3.1 (early 2008) right now, 24GB RAM , ATI 5770 , SSDs for system and scratch and HDDs for files . It's running well so far, but its age concerns me . Mainly I use it for heavy Photoshop work and some occasional 3D modelling . Used MP 5.1 are available for under 1K Euros here in Germany, including a decent amount of RAM, which got me thinking . So I did a lot of research, but am still a little confused . It seems a 2012 MP 3.33Ghz 6-core might be a good choice for me . A few years less under the belt than a 4.1 or early 5.1, so it will hopefully last for a bit longer . It'd allow for a faster GPU than my MP 3.1, maybe a PCIe SSD and a USB 3.0 card . A single Quad is not an option . Then again, I keep reading about how upgrading the CPUs in the dual-processor models of the MP 5.1 is fairly easy and affordable ( not so much with a 4.1 ) . I don't mind tinkering, but am not an expert , so I could only do a fairly straightforward processor swap . Any advice welcome !