Option Explicit
Const ADS_PROPERTY_UPDATE = 2
Dim objSysInfo, objUser, objNetwork, strComputer, strDescription

Set objSysInfo = CreateObject("ADSystemInfo")
Set objUser = GetObject("LDAP://" & objSysInfo.UserName)

Set objNetwork = CreateObject("Wscript.Network")
strComputer = objNetwork.ComputerName

strDescription = "Logged on " & strComputer & " on " & Date

objUser.Put "description", strDescription
objUser.SetInfo