May I ask, why?
Your post reminds me about the local computer store there is in my home town, called Inet and their wesite is inet.se/. The people who work there is friendly and helpful as they know a lot about what hardware fits together and what not fits. They also often take order for a pre-built computer from their customer and I would recommend that to anyone who aren't sure about computers in general, not saying you are, without promoting Inet.
So next time you want to get yourself a better computer than you have today then goto your local computer store, if there is one of course, and tell the people who work their what you want to have like; what video card, monitor, motherboard, how much RAM, and what kind of a CPU plus a good tower chassi and ask what is the best cooler for your next PC.