Problem with internal network on web server

ok, I've got quite a complicated problem to explain but hopefully there'll be an easy solution.

I've a vista pc which Im setting up as a web server and email server. It connects to the internet via a netgear wireless point connecting to a bt voyager v220 adsl router.

Externally if i go to Domain Names - Your Web Identity, domain name registration, top level domain names, domain name auction, domain name suffix information, i want to register a domain name, where can i buy a domain name, business domain names, domain transfer request f i get the live website being hosted by the vista pc (therefore I know the porting forwarding is working)
but when on the vista pc if i go to the same website i get the admin panel for the bt voyager router

Can anyone explain whats going on and how to fix it??

also, externally i can connect to the mail server using outlook, but internally i just get errors

Any help or advice wil be welcomed !!