Global Variables and Web Services

Question

I am building a Pocket PC app that loads uses a web service for authentication and has multiple forms. if I take the wireless LAN card out, it just hangs when I call the web service. Is there any way to check for connectivity before I make my call to the service so I can pop up an error instead? Also how can I share data between forms. I have some global variables that I want all forms to access. I tried creating a public class to contain all of my variables as properties, but wasn't sure which form to instantiate it from and how to reference it from the other forms. Any help is much appreciated.