URL validation in vb.net 2005

' URL validation
Public Function UrlIsValid(ByVal url As String) As Boolean
If url.ToLower().StartsWith("www.") Then url = "http://" & url
Dim webResponse As Net.HttpWebResponse = Nothing
Try
Dim webRequest As Net.HttpWebRequest = Net.HttpWebRequest.Create(url)
webResponse = DirectCast(webRequest.GetResponse(), Net.HttpWebResponse)
Return True
Catch
Return False
Finally
If webResponse IsNot Nothing Then webResponse.Close()
End Try
End Function