ttp://msdn2.microsoft.com/en-us/library/ms538121.aspx hIcon Windows 95, Windows 98, and Microsoft Windows NT 4.0 support icons of up to 4 bits per pixel (BPP). Windows Millennium Edition (Windows Me) and Windows 2000 support icons of a color depth up to the current display mode. Windows XP supports icons of up to 32 BPP.