Just remember that the U.S. Immigration and Naturalization Service
(the INS) is a fascist organization. They do their imperious, nasty and bureaucratic best to make it unpleasant for folks to visit the U.S., and they have alot of power, especially after 9/11. So when in doubt get a visa.
The guys and gals in the U.S. Coast Guard will treat you with respect (and risk their lives for you if necessary). But the INS is another story altogether. Avoid the INS at all costs.