"I have set up OE with 2 accounts, one for Wanadoo and the other for BT Internet. The problem is that when you click on the 'Send/Receive' button the 'Dial Up Connection' dialog box appears. This is no longer relevant as it is a Broadband connection. How can I prevent this appearing?"
Go to Internet Explorer > Tools > Internet Options > Connections and tick the "Never dial a connection option", click Apply and OK to exit.