Chris:

My applications include a Color Utility dialog that allows the user to pick the color of the controls depending of their intended use and value.

For examples:
1) A Financial textbox that changes color depending on whether its value is positive or negative (it can get mopre complicated depending on the intended use).
2) A Respond By textbox that changes value not yet responded and the date is near (another configurable value) or past.

The user can choose the Widows default colors or any other color scheme.

I don't like to rely solely on the Windows defaults because I believe:
1) the user should have the ability to choose the color scheme for individual applications.
1) special purposes controls can be enhanced by using color schemes specific to a range of value.
2) in not forcing the color scheme upon the user (why a lot of developers force a red background for negative dollar values is beyond me; it's makes it so difficult to read the value for a lot of people).

The other posters basically told you to use the Windows standard and nothing else. I prefer to comply to the Windows standard and let the user decides what color scheme are best for him/her. A standard is what is considered acceptable and correct by most users, and not by all users.

It's all about choices.

Daniel