I've been playing around with Thunderbird, but have never switched. I recently tried out PortableThunderbird, which is essentially thunderbird modified to run off of a USB drive. I had always kept my outlook .pst files on my thumbdrive before, and that was pretty much the main reason I hadn't switched over to Thunderbird before.
Now, with PortableThunderbird, I could get my mail from computers that previously had no e-mail client installed, Outlook or Thunderbird (since the installation is actually stored on your USB drive, and takes up about 10 megs). I'm real close to making the switch. Has anyone else doneso, and if they have, what are your impressions?