In Windows 7 you can easily change icon for any folder or shortcut via Properties. There a number of places in Windows 7 where you can locate buit-in icons. Some of them  are:

C:\Windows\system32\shell32.dll (General)

C:\Windows\system32\imageres.dll (General)

C:\Windows\System32\DDORes.dll (Devices)

C:\Program Files\Internet Explorer\iexplore.exe (Internet Explorer)