Reboot after install completes without logging in

I am deploying windows XP via RIS. I also have a bunch of Group Policies
that I want to be sure get deployed and sometimes the ones that install
software don't all get put on during the first boot and require a reboot to
get them all.

Currently in my rinstdnrd.sif file for automating the Windows setup I have
the following:

[GuiRunOnce]
"cmd /c Echo N|gpupdate /force"
"shutdown -r -t 120 -c This_Is_Important...Do_Not_Use_Until_Reboot"

When I logon for the first time it forces a GPUPDATE and then reboots the
computer. This works OK, but I still have to make a trip to the computer
again or RDP to it. I would like to avoid that.

Also, I can't use the Admin auto logon for the first boot because on of the
GPs I have renames the local Admin account for security purposes. I would
like to see if there is some what to run the GPUpdate command via the System
account just one time after install. This way everything will be assured to
be applied and ready to run with just one trip to the computer.