Is there a reason why the guide was taken down? Did JSC update it, or is the information outdated, or something? I'd really like to read it, since I've never built a computer before. Any help would be greatly appreciated in finding out what happened to it!
I would think with the forum update it moved the thread or otherwise changed the URL structure, making that link 404. I'l see if I can find it and update the link in the Troubleshooting sticky.
In the meantime, you can watch this video which goes through the build process (including test-benching/breadboarding the system).
Relevant part starts at 13:35, though it would be good to watch the whole thing. http://www.youtube.com/watch?v=qMRvz_IYSgM