Contact the Canadian Boating Safety Infoline at 1-800-267-6687 and ask for their booklet titled: Safe Boating Guide. Canada will accept any U.S. approved boat safety course. I made a copy of my Power Squadron course certificate and keep it with my registration. Canada's regulations are generally like ours except for a few things: they require PFD's to be bright colors (red, orange, yellow) and they require a throw bag. BUT non-Canada boaters are legal if they have the equipment required by their home country. So, if your boat is legal here, you can use it there.
Coast Guard assistance may take way longer in Canada then here, so I would invest in a portable GPS and VHF radio before the trip. Canada has many interesting and informative websites, including excellent weather info.
Finally, after 9-11, you need a passport to enter.