You are paying for Internet access and the ability to use MSN Explorer.
MSN Premium gives you MSN Explorer, eliminates ads from Messenger and Hotmail, and provides some other benefits such as WebRoot and McAfee for spyware/Virus protection, but you do not get Internet access.
If you do not need the Internet access and don't wish to use MSN Explorer, you can cancel the service and access your existing @msn email address using Windows Live Mail. It reverts to a free account.
-steve