You need to visit the Microsoft Script center :
http://www.microsoft.com/technet/scriptcenter/scripts/default.mspx
You can use a START UP SCRIPT (applied by a group policy) to change/set the
local admin password. That is what I do here, and it works great!. I apply
the script to the default domain policy to make sure every system gets the
startup script to change the admin password.
If you ever need to change the password again, it's as simple as modifying
the script and waiting for all your workstations to reboot (or you can force
this if you are a network Nazi !)
HTH
Drum on .. .. . . .