Dan3, why not? I do beleive that P4 4 Ghz will cherry-pop under 115 W by December. At present, extreme overclockers bring it to 5 Ghz or so. I just can't see it at 103 W, but 115 W is big enough to fit.
Another question - do you really want to have a box with 115 W cpu in your living room? How much noise it will make, how bad it will smell? Are you ready to pay $30-$40 per month of electricity bill for this box?