I bought a Dell XPS 8500 a few years ago for the purpose of using Autodesk CAD and Inventor programs, and as a good gaming computer. When I got the computer, it ran amazingly well, and I was extremely happy, especially for a guy that did not know much about computers. Recently though, I have noticed the computer seem to be slowing a bit, and I have been gaining interest in building my own PC. The problem is, I would like to keep as much of the hardware from this computer as possible and upgrade the rest, but I do not know where to start. I feel that the first thing to do is to transfer everything to a new case, but beyond that, I am clueless. I want to keep the Pc for a few more years and just upgrade as I go. Any help and recommendations on where to start and what to buy and anything else along those lines would be greatly appreciated. I will try to provide any information needed. Thank you very much.