Not sure how far you are down the road with this, but some people have used Aaron Stebner`s .net framework clean-up tool to uninstall and start at the beginning again. click here
It could take quite a while, though, and for some the gain is not worth the effort, but that`s for you to decide.
The problem is that there`s an awful lot to the .net framework and some parts are dependent on others and some are not. Simple, it isn`t.