Bob, you can go ahead and gasket the outlets, but unless this is wind-driven infiltration, the only thing you will accomplish is to move the draft somewhere else and make it even stronger. If you were incredibly diligent and took this to an extreme, you could even succeed in back-drafting your fireplace or combustion appliances (fortunately this would be a hard level to achieve). There is a very simple but vitally important concept to remember when dealing with air movement in buildings: AIR-IN = AIR-OUT, i.e. for each cubic foot of air that exits the house, one cubic foot of air will enter the house. Air would not be entering through the outlets if air were not leaving somewhere else, most likely through your attic. This is why the draft will be stronger in it's new location. You will have decreased the leakage area, but not the volume of required make-up air, hence the velocity of the infiltrating air must increase to make up the differance. So, you can chase the drafts from outlets to windows, to doors, etc. or you can plug the leaks where the air you paid to heat is escaping, i.e. air seal the attic-floor/ceiling boundry. For more information take a look at www.weatherization.com.