Systems Management

i use autohotkey to compile a exe, and then push it via psexec or a logon script.

MsgBox, 4144, Message From Administrator, Your Computer needs to restart. Please Press OK to restart now.
Shutdown, 6

The "4144" makes it so that the user can only press ok and it stays on top.  "Shutdown,6" restarts the computer without interuptions.
Then use psexec like so to push it to the user (assuming your admin on a domain)...

psexec.exe \\ComputerName -s -i -f -c C:\reboot.exe

where C:\reboot.exe is where you compiled your autohotkey script.

You can download a pshutdown from microsoft (sysinternals).

http://technet.microsoft.com/en-us/sysinternals/bb897541.aspx

If its a script you wanted then you can use the following

Set WSHShell = WScript.CreateObject("WScript.Shell") 
Set oFS = CreateObject("Scripting.FileSystemObject") 
 
strWarning = "Due to network maintenance, this computer must be restarted. You have 5 minutes to save your work from the start of this countdown. Sorry for any inconvenience caused. " 
strDelay = 300    'Delay given in seconds; change this value to your preference, or set it to 0 to give no delay at all 
 
'Open a text file of computer names 
'with one computer name per line 
Set oTS = oFS.OpenTextFile("C:\computers.txt") 
 
'go through the text file 
Do Until oTS.AtEndOfStream 
 'get the next computer name 
 'store it in variable strCompname 
strCompname = oTS.ReadLine 
        WshShell.Run "C:\Windows\System32\shutdown.exe -m \\" & strCompname & " -r -c " & Chr(34) & strWarning & Chr(34) & " -t " & strDelay    'Replace the "-r" switch with "-s" to make the computers shutdown instead 
Loop 
'close the text file 
oTS.Close

You can write a VBScript to do this activity.

Refer the following links

http://blogs.technet.com/b/heyscriptingguy/archive/2005/02/17/how-can-i-count-the-number-of-times-a-user-has-logged-on-to-a-computer.aspx

http://www.hofferle.com/reboot-logoff-or-shutdown-a-remote-computer/