For system administration purposes, both Windows XP and Windows 2000 Professional systems share the root of each drive. By default, this “folder” is shared using a name created by taking the drive letter (such as C) and appending a dollar sign ($) to the end of it. On a Windows XP/2000 Professional system, these administratively shared folders are only accessible to administrators.
The $ symbol following the drive letter hides the share, ensuring that it is not displayed in My Network Places, Network Neighborhood, or when the NET VIEW command is issued. In order to access hidden shares, an administrator would typically map a network drive or enter the path at the Run command – for example, \\192.168.1.100\C$. To that end, for a higher degree of privacy, consider hiding all shared folders on your network by appending the $ symbol to the end of their share name – such folders will still be accessible over the network, but only to users who know and can provide the correct path.
On Windows XP Home systems, the root of each drive is not shared automatically, but can be by accessing the properties of the drive if required. As a general rule, avoid sharing drives from the root, since the careless assignment of permission potentially exposes the contents of the entire drive to anyone who can connect to it. This can lead to the malicious or accidentally deletion of critical system or data files, something you’ll want to avoid at all costs.