Like Glenn said. Print preference defaults are not set through print dialogs in applications, they're set through the list of printers in Windows.

Start > Run > "control printers"

They did it that way so that you could change settings for one print job and not have it screw up every following print job. The main example is when companies will set the default printing to black and white to save money, but still gives their users the ability to change it to color when they need it.