Amra, the putty in your holes would pop and ruin your paint job. I also think you would run into problems if you are countersinking into MDF (not enough meat left for good support). Your concept is acactly what he needs though.
I've been incorporating the same thing into my design. Look at it this way, your cabinet is really made up of a 2x4, 2x2, and 1x2 chassis. The outer MDF is just the covering, and can be made to be taken off. You do need to come up with a good way to do this, because it can't _look_ like that is how you built it.
Good suggestion though.
RubberDug, I partially agree that this is a hard project and not necessarily for someone who has done no woodworking. However, if you have the time and money, then go for it. Keep in mind though, if you don't have some woodworking skills, be prepared to have to redo every single piece of wood you cut. If you can't afford to buy two extra sheets of MDF because you cut the first ones wrong, I'd be worried. I like the "Family Handyman" magazine because they do a good job of detailing woodworking projects. What I really like is that they include little "snippits" of what they do wrong. The problem I have with Norm is that you never see him mess up. EVERYONE will mess up at some time. Hopefully you mess up on a 4x8 sheet of MDF and not on a 3'x3' panel of Cherry!