If Bush manages to amend or override the constitution so that he stays in office past noon on January 20, 2009, then this is a discussion worth having. Until then, I think we do have a pretty good constitution that gives the populace the power to keep one person from weilding all the power or from staying in office past his term. I don't even think the Patriot Act granted Bush that kind of authority.
For the record, I do not support President Bush on 90% of his agenda. But a tyrant he isn't.