We often preach how easy it is to roll your own rig, once you know how. And even if you don't, it's not hard to take that next step -- all it requires is a little bit of research, some careful planning, and the right parts.
One of the best ways to learn how to piece together your own system is to build up experience by upgrading your existing PC. If you think about it, a full system install is really just one big upgrade, and some of the steps are so easy even a chimpanzee can do it. Literally. Don't believe it? Check out Mushkin's new video showing a chimp installing a kit of RAM, and then celebrating (which is perfectly acceptable after completing your first build/upgrade).
Pretty lame. After the write up, I honestly thought the monkey was going to install the RAM, and not a bunch of fancy camera work while a man in a glove installs the RAM.