vbscript to check if a computer is available

Option Explicit
dim objPing
dim objStatus
dim strComputer

strComputer="." 'IP Address or Name
Set objPing = GetObject("winmgmts:{impersonationLevel=impersonate}")._
ExecQuery("select Replysize from Win32_PingStatus where address = '" & strComputer & "'")

For Each objStatus in objPing
 If  IsNull(objStatus.ReplySize) Then
  WScript.Echo "computer is offline"
  '...
 Else
  WScript.Echo "computer is online"
  '...
 End If
Next

Set objPing=Nothing
Set objStatus=Nothing