I decided to uninstall Internet Explored 5.5 yesterday on my laptop. I was experiencing slow actions in Windows Explorer and I have heard this is a probable cause. During the uninstall I saw a reference to Outlook Express (my e-mail program) and I checked that box. My understanding was that Outlook Express would roll-back to the previous version, just as IE was supposed to.
Now, on starting up my computer, I see Outlook Express is gone, therefore I don't know if my e-mail messages are gone. I am currently downloading I.E. 5.5 with Outlook Express. After the install I will know. Unfortunately, I had some e-mail messages that I was saving, such as program registrations, so I better not have lost it all!