Will have to think more on this. We do have a a domian policy for Windows Updates, that mostly works; it never seems to work as intended. In any case, if a Citrix driver is updated, with the registry setting set, it will reboot x number of times? (3 is suggested I believe)
Wish there was a bomb proof method. Just this morning I came to office to find half the building down, because MS decided to push a Citrix update last night, and the DHCP server was down, until I rebooted the VM from the console once more. ;(