By default in Windows XP Service Pack 1 (SP1), if you click
the Sharing tab of the Properties dialog box
for the folder, and then share the folder for other users to access over the
network, the folder has permissions that give everyone read-only access. In
versions of Windows XP that are earlier than SP1, if you share folders by using
the Sharing tab of the Properties dialog box,
the folder has default permissions that gives everyone full control.
NOTE: This behavior is not true for folders that you share by using
the New File Share Wizard and the Net.exe command. These folders continue to
have default permissions that give everyone full control.
These changes to the default permissions settings are part
of the security enhancements in SP1.