Here's a script I got from ASPFAQ.com:
<% Response.Buffer = true %>
<%
url = "
Set objWShell = CreateObject("WScript.Shell"
Set objCmd = objWShell.Exec("ping " & url)
strPResult = objCmd.StdOut.Readall()
set objCmd = nothing: Set objWShell = nothing
strStatus = "offline"
if InStr(strPResult,"TTL="

>0 then strStatus = "online"
response.write url & " is " & strStatus
response.write ".<br>" & replace(strPResult,vbCrLf,"<br>"
%>
There are also scripts for XP and .NET on this page,
Hope this helps!