In Windows Mail, go to Tools, Accounts, select the account, Properties,
Connection tab, and make sure the settings there are grayed out, indicating
that IE's settings will be used.
When you open Internet Explorer, does it try to dial? If so, go to either
Internet Explorer/Tools/Internet Options or Control Panel/Internet Options.
Click on the Connections tab. Make sure "Never dial a connection" is
ticked. In fact, all the dial-up settings should be grayed out, indicating
that Vista recognizes the presence of an Internet connection via the LAN.
Gary VanderMolen