you can also use this, and then you get access to everything listed here
http://msdn2.microsoft.com/en-us/library/ms649274.aspx
code:
function getSpecialDir( CSIDL){
var szSendToPath = Interop.Allocate((255 *2) +2);
Interop.Call("Shell32", "SHGetSpecialFolderPathW", 0, szSendToPath, CSIDL, 0);
return szSendToPath.ReadString(0);
}