Funnily enough it's almost exactly the same as the project I'm working on at work.......an X-Y routing machine that cuts out the glass openings in doors......
Even more funny, I have a page on my website dedicated to a DIY 3-axis CNC. I also have a very popular thread on my message board dedicated to those
getting it to work. Lots of good info there IMHO.
http://www.grabercars.com/content/view/67/2/
Cheaper on Amazon! 
Link