I have owned a mac pro since around 11/2012. It is a 12-core 3.06 with a 512GB SSD and an ATI 5870 and two 27" ACDs. I have been extremely happy with this machine. No, it wasn't inexpensive, but the build quality, reliability, performance, and versatility are top notch. I hear many complain that the technology is "2009" technology, which may be true to an extent, but it was top of the line 2009 technology. The fact it can run so many OSs is very attractive for me. As far as I know (I have tried many) the machine will run the following native without virtualization: OS X 10.6.4+ OS X 10.7.x OS X 10.8.x Windows XP SP2/3 Windows Vista x86/x64 Windows 7 x86/x64 Ubuntu Solaris ESXi 5.1 With the fit and finish of the case, the power of the Xeons and the expandability with 128GB of RAM, I must say I have been extremely happy with this machine. I am not a gamer, so I don't use it for such tasks, but I am sure it would do just fine if one wanted to - especially if one put a newer GPU in it, but that would cut off the OS X options so I am not up to doing that just yet. I also see many 1,1 models to 4,1 models in use, and that is very impressive. I certainly would not hesitate to buy another one (older/refurb) as a second machine. When the 6,1 is released, I hope they do not change the design of the machine. That is one thing I love about it. I hope they keep the two optical bays. The only things I would wish for would be the additional of USB 3.0 standard, Thunderbolt, and newer EFI version to boot Windows 7 x64 native EFI, but these are very minor issues and do not affect my opinion of the current machine.