Unfortunatley, for your average home user, there's so much rubbish strewn all over the place (registry, dlls etc.) that it's simply not going to be feasible. And I think it's safe to say you'll never see "MS making it the standard".... it's too complex a challenge.
Suggest you take a peek at something like Faronics DeepFreeze (
faronics dot com)
Otherwise, take a leaf out of the corporate books. Format one last time, create a clean image to your liking..... ghost it ..... hey presto.... when combined with regular backups, you're back to a clean state that's not too far off where you were.