To change the icon of a certain folder simply right click on the folder and choose Properties, then select the Customize tab. Click on Change Icon and choose a new icon from the window that appeared. You can also choose some other files with the .ico extension, by pressing the Browse button. Then click on OK and then again on OK. The same settings apply to Windows XP, Vista and 7. If you want some nice, new icons, you can download some from here: http://www.freeiconsweb.com/