try this, and set it up as a scheduled task to run every few minutes or whenever:
'=======================================================
' Name: ping.vbs
' Date: 10/02/05
' Fersiwn: 1.1
'------------------------------------------------------
' Change these:
ipcheck="
tempfile="c:\pingtemp.txt"
logfile="c:\ping.txt"
'=======================================================
Set wshShell=WScript.CreateObject("WScript.Shell")
Set fso = CreateObject("Scripting.FileSystemObject")
Const ForReading = 1, ForWriting = 2, ForAppending = 8
Const TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0
wshShell.run "cmd /c ping -n 2 -w 20000 " & ipcheck & " > " & tempfile, 0, True
Set tempfile = fso.GetFile(tempfile)
Set ts = tempfile.OpenAsTextStream(1)
strResponse = "Nid yw'ch cyfrifiadur yn gweld y gweinydd."
gweldgweinydd="false"
Do Until ts.AtEndOfStream = True
If InStr(ts.ReadLine, "Reply") > 0 Then
strResponse = Now()
pingcomplete="true"
Exit Do
End If
Loop
ts.Close
if pingcomplete="true" then
Set logtxt = fs

penTextFile(logfile, ForAppending, True)
logtxt.WriteLine(strResponse)
logtxt.Close
end if