I'm using
Opera, which has an email client, newsreader, etc integrated into the browser and that's probably what I'll stick with. Its newsreader is top notch.
I'm still not too happy with Firefox melting down on me several months ago after installing version 1.5. Yeah, yeah, yeah, I know you can do this, that and the other to get the bookmarks back and anybody who can't figure it out is a moron, but I don't have time to constantly tinker with it. And I like Opera's mail client better than Mozilla's Thunderbird.
I would recommend the
Sage extension for Firefox users. I didn't care much for the newsreader function on Thunderbird (Mozilla's email client), which usually has you viewing the web page in Thunderbird, but having to pull it up in Firefox if you want to comment, etc.
Can't help you for IE since I haven't used it as my default browser in well over a year, although I think Outlook Express probably has a newsreader if you use it.
[Edited on 4-6-2006 by Pilgrim]
[Edited on 4-6-2006 by Pilgrim]