Building A Computer From Scratch?

wackybrit asks: "The economy has given many of us the chance to go and work on some side projects. I was reading "Interview With Bill Gates" and have been inspired to create my own computer from parts, to write my own interpreter, and to really see if I could do what Gates and Allen did back then. With the Internet as a reference guide, it should be easy. However, things are not always so easy. I might be a techie, but I have no idea how memory chips hook up, how a data bus really works, and how to tie everything up. Do you Slashdot folk have any handy tips or resources I can refer to for building my own machine from scratch?" If you had a chance to build your own computer, would you make yours similar to existing designs (ala the PC, or the Mac), or would you do it differently?