Moving from Outlook Express to Thunderbird
If you don't know, Thunderbird is a stand-alone mail client, created as a redesign of the Mozilla mail component. I'm considering switching our office from using Outlook Express to Thunderbird, mostly because keeping up on the patches for OE is a pain in the butt, and OE doesn't have built-in spam filtering .If you need more reasons, Neil has a pile of reasons why he thinks Thunderbird is superior, I still use Outlook 2002 myself, as I use its scheduling functions quite a bit, but if I didn't need them, I'd be using Thunderbird.
But here's the trick: Making the move from OE to Thunderbird as seamless as possible. For this, you just need to read this step-by-step guide, and a little motivation. As the article points out, if you're using OE because you can check your Hotmail account from it (now there's a compelling reason to keep OE -- so you can download all your Hotmail spam as well as your normal spam), Hotmail Popper will allow you to access your Hotmail e-mail from any client.