VBS - last reboot time

strComputer = "." ' Local computer

set objWMIDateTime = CreateObject("WbemScripting.SWbemDateTime")
set objWMI = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
set colOS = objWMI.InstancesOf("Win32_OperatingSystem")
for each objOS in colOS
    objWMIDateTime.Value = objOS.LastBootUpTime
    Wscript.Echo "Last Boot Up Time: " & objWMIDateTime.GetVarDate & vbcrlf & _
        "System Up Time: " &  TimeSpan(objWMIDateTime.GetVarDate,Now) & _
        " (hh:mm:ss)"
next

Function TimeSpan(dt1, dt2)
    ' Function to display the difference between
    ' 2 dates in hh:mm:ss format
    If (isDate(dt1) And IsDate(dt2)) = false Then
        TimeSpan = "00:00:00"
        Exit Function
        End If

        seconds = Abs(DateDiff("S", dt1, dt2))
        minutes = seconds \ 60
        hours = minutes \ 60
        minutes = minutes mod 60
        seconds = seconds mod 60

        if len(hours) = 1 then hours = "0" & hours

        TimeSpan = hours & ":" & _
            RIGHT("00" & minutes, 2) & ":" & _
            RIGHT("00" & seconds, 2)
End Function