Prevent someone else from peeking at your Windows 2000/XP system:

If you have a Windows 2000 or Windows XP machine connected to the Internet, chances are good that your computer's security information, including user profiles, account policies, and share names are freely available to any hacker on the Internet.
This is because, by default, Windows 2000 and Windows XP do not restrict anonymous access to the above listed information.
However, you can very easily prevent others from gaining access to this sensitive information on your PC by making one very simple change to the Windows Registry.

Here's how:
1. Click on the Windows Start button.
2. Click Run.
3. Enter "Regedit" in the Run Box and click OK.
4. The Windows Registry Editor will open.
5. Drill down through the Windows Registry to get to the following key:
6. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\LSA
7. Locate the key named restrictanonymous.
8. Double click on this key to edit it.
9. Set this key's value to 1.
10. Reboot your PC.

This setting will prevent enumeration (listing) of the Security Accounts Manager (SAM) settings on your PC. If that level of security is not strong enough for you, you can also set this key value to 2, which means that no one can access any account information on your PC without explicit anonymous permission.