In general you just want to make sure that everything is compatible with each other. The first place I start is with the motherboard and processor. If you have a specific type of processor that you like then you can start with that, I usually like to put AMD processors into my machienes so I\'ll look for an AMD board to start with, so for example, I recently upgraded to the new FX series processors from AMD so I shopped around (mostly on newegg.com) and looked up boards that were compatable with the type of processor that I wanted to put in there. Then I just made sure that the board had things on there that I wanted. I made sure that it had a proper video card slot, that the board supported the ammount of RAM that I wanted to put into my machiene, if it had SATA 6.0Gb/s ports for the hard drives and whatever else I wanted with it. Once you have those two things its pretty much just fill in the holes after that. Just pick yourself up a video card, a hard drive, an OS, and whatever other things you want to put in it. Just make sure that you get compatible RAM for your motherboard and a Power Supply Unit (PSU) to make sure things stay powered and thats pretty much it. Newegg has nice little helpers to show you which RAM is compatible with your board and an estimator on how much power you will need to run your machiene so they make it pretty easy to get yourself up and running. Hope this helps!