Dude, you are gonna be flamed. But rather than do that, I'll help ya out.
I don't know of anybody with a Contour that has done it, but there was a guy with a Cougar that was successful. Here are some recent threads on the subject.
ATX to MTX, need list of parts ASAP
ATX to MTX
ATX to MTX
Successful ATX to MTX swap
Going from ATX to MTX
ATX to MTX conversion?
Here is some reading for you to do. And remember, search is your friend. Make sure you use it or the search nazi's will get ya.
Hard-Core baby! 
