I just found this that might help! http://ldd.lego.com
EDIT: I forgot to add. After you design what you want there. You can actually send the plan to Lego and they will ship you the blocks you need and it will make building intructions!!
THATS AMAZING! Should have seen it sooner.
But. . .We got it working anyways.
I'm so proud of me and my 2 partners. We told our prof. what we wanted to do, and he looked at us like "what..the..hell?" No one had every tried it and he didn't know what to expect.
We decided to make it EVEN more difficult than just a "p.c. in a lego case." We decided to put an X-Box AND Computer in the case. We did it!
WOOT!We ran out of lego's at the end - Go figure. We used about 2600 Lego's. We didn't have enough lego's to make a roof over it...brilliant idea. "We didn't make a roof so you can see what we did!"
I'll post pictures of it soon, it looks ugly because of the color differences in the lego's. Dumb partner got rainbow colors!

Heh.. Our immature-selves had to put a penis on the side of the case. LOL. We also made our college logo on the left side. It looks awesome.
www.ycp.eduIts the white/green "Y".
The computer runs and the we played halo on the X-Box, I'm so impressed. If we don't get an A+++ then everyone else should get F---!
Most other groups just tried to get "linux running on a computer, and play unreal tournament." Soooo hard!
I'll post pictures soon!