Well, I believe I learned a few years ago that most of our oil was from Venezuela and Mexico, and a quick check at the US Department of Energy website yielded the following results (as of 2003):
Venezuela: 1,385,000 bbl/d; 11.3%
Mexico: 1,639,000 bbl/d; 13.4%
Canada: 2,068,000 bbl/d; 16.9%
Saudi Arabia: 1,772,000 bbl/d; 14.5%
Iraq: 470,000 bbl/d; 3.8%
*percentages are of oil imports, and exclude the oil the US provides itself
Also, it lists the top suppliers (imports, that is) of oil as: Canada, Mexico, Saudi Arabia, Venezuela, Nigeria (in that order). So it still stands that Iraq is not the main source of oil to the US.
As far as US oil production capabilities, we currently (2003) produce 7,800,000 bbl/d. This is 39% of our consumption, so we are our main source of oil. Also, this excludes all the oil we choose not to extract. Now granted, we still need foreign oil to meet our demand, I never said otherwise. My point was just that our eggs aren't all in one basket.
Relevant links:
http://www.energy.gov/engine/content.do)
http://www.eia.doe.gov/emeu/cabs/contents.html)
http://www.eia.doe.gov/emeu/cabs/usa.html)
http://www.eia.doe.gov/emeu/cabs/venez.html)
http://www.eia.doe.gov/emeu/cabs/iraq.html)
EDIT: Just realized your comment was about oil reserves, mine was about potential production, although my figures were current production. I wasn't able to find what I was looking for as to potential, though I didn't try very hard.