Default-hidden shares are

The default-hidden shares are:

• C$ D$ E$ - Root of each partition. For a Windows NT workstation/W2K/2003/XP Professional computer only members of the Administrators or Backup Operators group can connect to these shared folders. For a Windows NT Server/W2K Server computer, members of the Server Operators group can also connect to these shared folders.

• ADMIN$ - %SYSTEMROOT% This share is used by the system during any remote administration of a computer. The path of this resource is always the path to the W2K/NT system root (the directory in which W2K/NT is installed usually C:\Winnt and in XP it's C:\Windows).

• FAX$ - On W2K Server, this used by fax clients in the process of sending a fax. The shared folder temporarily caches files and accesses cover pages stored on the server.

• IPC$ - Temporary connections between servers using named pipes essential for communication between programs. It is used during remote administration of a computer and when viewing a computer's shared resources. This share can be very dangerous and can be used to extract large amounts of information about your network, even by an anonymous account.

• NetLogon - This share is used by the Net Logon service of a W2K, 2003 and NT Server computer while processing domain logon requests, and by Pre-W2K computers when running logon scripts.

• PRINT$ - %SYSTEMROOT%\SYSTEM32\SPOOL\DRIVERS Used during remote administration of printers.

It is possible to simply remove the share from Server Manager (in NT) or Shared Folders (in W2K/XP/2003) but the problem with this method is that the shares will automatically be recreated when the machine reboots.

You can disable the automatic administrative share creation via Group Policy, but this is a much simpler way:

Source: http://www.petri.co.il/disable_administrative_shares.htm