Once you have shared a resource (a disk or folder or printer) in Windows XP Professional or
Windows XP Home, you can check the access to these resources via the network:
select in the Control-panel : "Administrative Tools" : 
Management of Shared Folders is part of "Computer Management" :
Select in the left Tree-View Window under "System Tools" : "Shared Folders":
Under "Shares", you get the display of all shared resources, either defined by a user or
the invisible System Shares (names with the "$"-sign at the end ) :
Under "Sessions", you get a list of Users (and the name of their computers), which are
currently connected via the network to your system :
 | To terminate a session ( to disconnect a user), right-click on a user and select to "Close Session" If you right-click in the list-windows BUT NOT on any user, you get a different pop-up menu allowing to "Disconnect All Sessions" |
Under "Open Files" you get a list of all folders and files in use via a network user :
 | To close a file, right-click on the file and select to "Close Open File". |
When you are using your Windows XP system as a File-server of a network of system,
how many systems can connect (use a shared resource ) at the same time to a Windows XP-system ?
| - | Windows XP Professional : 10 simultaneous file-sharing connections ( same limitation as in Windows NT4 workstation and Windows 2000 Professional ) |
| - | Windows XP Home Edition : 5 simultaneous file-sharing connections ( Windows 95,98, ME do not have a known limit of simultaneous file-sharing connections ) |
Source of this information :
Microsoft Windows XP Professional Resource Kit Documentation
Appendix G: Differences between Windows XP Home Edition, page 1539