On Vista/Win 7, I have seen code where only a single period is returned for (0). This makes sure you get the actual IP regardless of the system.
Const IPPattern As String = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"
With Dns.GetHostEntry(System.Environment.MachineName)
Return .AddressList.Where(Function(a) _
Regex.IsMatch(a.ToString, IPPattern)).First.ToString
End With