SBS2008 can take forever to reboot so here is a quick script to reboot very quickly.
So just copy this into notepad and save it as a batch file. When I was installing Exchange SP3 last night it was getting late so I ran a scheduled task to run this batch file and it works fine.
net stop msexchangeadtopology /y
net stop msftesql-exchange /y
net stop msexchangeis /y
net stop msexchangesa /y
net stop iisadmin /y
shutdown /r /c "Scheduled Restart" /f