Copy 'My Documents' to Network Drive

I have an external network storage device and I would like to make a copy of
the 'My Documents Folder' to the network drive, Every time a file is created
or modified windows automatically creates or modifies the file on the
network drive.

Is there a registry mod or simple script that can achieve this without the
need for additional software?
I have seen this used where I work and wonder how to achieve the same?

All computers using Windows XP Pro SP2 and a wired network with an SC101
drive.

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