One of my latest projects is to put a PC inside a VIC-20 case. I already have the very small system board built, with an OS installed and the VICE emulator.
I will be putting updates on this project on the following page. http://retrocomputers.wordpress.com/the-vic20-pc/
Make sure you check out this page in the next couple of days. I will be posting photos!
(Edit : Ive changed the system from Commodore 64 to the VIC-20 + corrected the link to the project page)