OK, I guess my post has been debunked by Norm, but you might want to take a look at this, from OVERVIEW OF TAX CONSIDERATIONS FOR CANADIANS IN THE UNITED STATES
"Generally, a foreign citizen is treated as a non-resident for United States tax purposes, unless he or she meets one of the statutory tests for residency. These tests are: (a) the Lawful Permanent Resident test, and the Substantial Presence Test. The lawful permanent resident test would not apply to Canadians who are in the United States temporarily. However, most Canadians in temporary status would probably meet the Substantial Presence Test, which is based on physical presence in the United States.
A foreign national will meet the Substantial Presence Test if he or she is present in the United States for 31 days in the current year and the sum of the following:
sum of the days present in the United States in the current year,
one-third of the number of days present in the first preceding year,
one sixth of the days present in the second preceding year equals or exceeds 183 days.
There are limited exceptions for foreign government employees and professional athletes. Canadians who regularly visit the United States for business or pleasure and meet the Substantial Presence Test, will be treated as residents for United States tax purposes. However, a "Closer Connection Exception" is available if all of the following apply:
the alien has been present in the United States for less than 183 days in the current year;
the alien has maintained a permanent place of residence in Canada throughout the current year; and
the alien files Form 8840 by the due date, usually June 15th of the following year.
If a Canadian meets the Substantial Presence Test but is ineligible to meet the Closer Connection Exception (i.e. since he or she is present in the United States for more than 183 days in the current year), he or she will be considered to be a resident alien of the United States. Resident aliens are taxed on worldwide income in the same manner as United States citizens."
I guess I would still talk to a tax lawyer. Or Norm,