Thunderbird 1.5 has been finally released just a couple of days ago. You can go ahead and download a copy here.
If you’re still stuck wiht MS Outlook or Outlook Express, you’re missing out on something here. Give it a try. Just use the IMAP settings instead of POP so you’ll retain all your emails on the server.
Like the Firefox, Thunderbird has extensions and themes too.
i’ve been using Thunderbird for about 3 years now and i really like it. it does an excellent job in filtering spam. i also use a third party program that lets me download my Yahoo mails to my machine and still keep a copy in my web inbox. yeah, IMAP is better than POP becoz you keep the emails in the server unless you delete it. :)