AFAIK there is no desktop directory, just the desktop. If you are trying to view your drives, folders and files, you can use the shortcut:
Start>All Programs> Accessories>Windows Explorer. If you right-click on the icon, you can send a shortcut to your desktop.
Ahem... C:\Documents and Settings\username\Desktop. This however does not actually get you to your "Desktop" but rather shows you the files you placed on it.
If you want to get to your desktop as in the main Windows screen, there is a "Show Desktop" icon that by default is in the Quick Launch toolbar.