I think that following these instructions will allow you to change the application background color. However, depending on what color you choose, you may also have to select a new font color. The full text of this can be found at:

http://support.microsoft.com/default...b;en-us;310543
How to Change the Color, Size, and Font of Individual Window Elements

To change the font, size, or colors of individual Window elements, follow these steps: 1.Right-click an empty area of your desktop, and then click Properties.2.Click the Appearance tab, and then click Advanced.3.In the Item list or in the preview window, click the Window element that you want to change. You can select from any of the following items: 3D Objects
Active Title Bar
Active Window Border
Application Background
Caption Buttons
Desktop
Icon
Icon Spacing (Horizontal)
Icon Spacing (Vertical)
Inactive Title Bar
Inactive Window Border
Menu
Message Box
Palette Title
Selected Items
ToolTip
Window
4.Do any of following to achieve the look that you want:

NOTE: Not all options for all Window elements are available. For example, the Font option appears dimmed and is unavailable for elements in the Item list that do not display text. •Under Item: •In the Size box, specify the size that you want to use for the item.•In the Color box, specify the color that you want to use for the item.•Under Font: •Click the font that you want to use for the item.•In the Size box, specify the font size.•In the Color box, specify the color that you want.•To apply a bold font, click B. To italicize the font, click I.A preview of your current settings is displayed in the preview window.

5.When you are finished making the changes that you want, click OK twice to save your settings.NOTE: •If you click Window in the Item box, and then modify the font color for that item, the automatic font color that is available in many programs is also modified. Any documents that use the automatic font color are affected if you change this setting. Many programs, including WordPad and Microsoft Word, use automatic as the default font color. Any new documents that you create in these programs use the new font color that you select for the Window item.

To use a different default font color in programs that use automatic as the default font color, you may be able to create a template that uses the font color that you want as the default font color, and then use that template instead of the default template. For information about how to do this, view the documentation that is included with the program, or contact the program manufacturer.•As you modify items, note their appearance in the preview window. Note that you must use the same font and size for the Active Title Bar and Inactive Title Bar items, and that bold or italic selections for either item are applied to both items. If you choose a desktop theme after you change fonts or colors, the fonts and colors for that desktop theme override your selections.