Just a quick update - I've since been using Thunderbird and was pretty surprised to notice that it seems to integrate with FireBird on its own. I got an email notification with a small notice box popping up at the bottom-right corner of the screen, like how it is with MSN messenger. Thunderbird was not running at the time - it does make you wonder if this can be stopped, since I didn't ask for email-polling explicitly.

Nevertheless, I'd have to say that is pretty cool ;).