Paul Boyer, better known as Mormegil, has put together a series of WinCustomize articles called Icon-A-Day to show people how to create their own slick looking icons.
This series of articles will tech you how to create your own icons for Windows XP.
Read the Icon-A-Day Articles: Icon # 1, Icon # 2, Icon #3, Icon # 4, Icon #5, Icon # 6, Icon # 7, Icon #8.