If  Windows Vista’s default appearance and sounds aren’t to your taste, you can change them with a different desktop theme– a stored set of colors, icons, fonts, sounds, and other elements that redecorate your desktop. You can pick a predefined theme or create your own.

To set a theme in Windows Vista:

1. Choose Start > Control Panel > Appearance and Personalization > Personalization > Theme.

or

Right-click an empty area of the desktop and choose Personalize > Theme.

2. From the Theme drop-down list, choose a theme.

3. Click OK (or Apply).

Here are some more Tips:-

• To populate the Theme list, Windows looks in your Documents folder and in \Windows\Resources\Themes. Choose Browse from the Theme drop-down list to open a theme located elsewhere.
• Windows comes with only two themes, but many others are freely available. Try www.dowtheme.com and the Themes section of www.download.com or www.tucows.com. Movie and game sites have them too. Choose Browse from the Theme drop-down list to load a downloaded theme (.theme file). For an extreme makeover, try WindowBlinds (www.windowblinds.net).
• Select the Windows Classic theme to restore the look of Windows 98/2000.