Just how much power does the Commerce Clause give Congress?

Members of congress believe the Commerce Clause gives them enormous power to control Americans, most recently evidenced in Health Care legislation's requirement to purchase insurance.

Perhaps they are being too modest in their grasp of power. Consider the wording of the Commerce Clause:

Article. I, Section. 8, Clause. 3: (Congress shall have the power) To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes;

The Clause provides the same power over foreign Nations as over the States. Therefore, Congress really has the power to control the world! Woo-hoo! You rule the world, Nancy!

But in reality I see Congress having the same power to force anyone in Tennessee or Switzerland to buy insurance: none.