Whirly, there is rarely a reason why you should have to disconnect from one ISP to check mail on another mailbox. Whilst I am not a PC user (Mac is the way) I check mail in at least 5 different accounts on other domains from one email program. You should have some option so that Outlook Express can check the email in all your accounts at the same time.
Glad that you find PPRune useful for more mundane things.