Connecting two networks via Tunnle

Hi,
I have two networks windows 2000 which I have connected via Tunneling through the internet with cisco router 2620 my tunnle works but I am unable to see in my network, all the domains , and some of the domains I can see but cannot brows. If I go into the computer via the ip address I can get into them.
I have added Ip helper and Ip fowarding Plus as I mentioned above some of the domains I can see.

Thanks

Darryn