Over the weekend I have built the MCU for the $50 robot. Although the tutorial was excellent and described each step nicely, I felt I should write up my own experience building it, giving tips and advice that helped me as well as identifying anything I had a problem with. I have posted this information in my blog. I hope this helps someone.
Blog Link: http://marksproject.blogspot.com/2008/08/my-first-brain.html