Logon / Logoff Scripts - Walpaper

First things first:
 - I have a Windows 2000 Advanced Server, server
 - Between 50 and 75 Windows XP PC's - some user use laptops
 - About 100 Users

Is there a premade logon / logoff script that loads a particular
wallpaper and stores it in the users are on a server. I would need it
to be both logon and logoff as i would want it to dynamicly update the
picture.

ie. if a user changed thier wall paper it would load on a differnt
machine on the network

i could configure the wall paper using the OU but thsis would not be
customisable and it would take too long.

Tarl