For the Zetec the turbo will be better than a supercharger, because the supercharger is belt driven. Therefore you will be losing power to get somemore power. The turbo is exhaust driven so it won't take any initial power off the engine.
I believe the turbo is better hp rating for you money. There are a few kits available.
EDIT: Also try a search on this subject. It has been talked about a lot in the last few weeks!!!!!
