Nice script mavhc, someone just asked almost the same question here Script Help - Query AD and add it to a reg key and I used your script as a basis with a small alteration to make it work by writing registry keys instead of fireing up an office app to do this.
Code:
On error Resume next
Set ADSysInfo = CreateObject("ADSystemInfo")
Set objUser = GetObject("LDAP://" & ADSysInfo.UserName)
Set WshShell = WScript.CreateObject("WScript.Shell")
regpath = "HKEY_CURRENT_USER\Software\Microsoft\Office\Common\UserInfo\"
UsersName = objUser.givenName & " " & objUser.SN
UsersInitials = Left(objUser.givenName, 1) & Left(objUser.SN, 1)
WshShell.RegWrite regpath & "UserName", UsersName, "REG_SZ"
WshShell.RegWrite regpath & "UserInitials", UsersInitials, "REG_SZ"