I've been moving towards CSS-based layouts at my work. And I hadn't thought we were required to support IE 5.5, but I was mistaken. A few of the layouts I did required a minor change to work with IE 5.5, but since the sites had already been released I needed to defend my logic for not supporting that browser. So for my future reference, here is what I (actually my husband) dug up (in case I ever need to use it again)
You can see a quick summary here. And you’ll see the note that says security updates and support for IE 5.5 ended on December 31, 2003.
As well, you can see on this page that all "flavors" of IE 5.5 support (including security updates) from Microsoft have all ended with the exception of windows ME – but even that particular version has this note associated with it:
Microsoft strongly recommends customers install the latest released version of Internet Explorer, which provides improved security protection.
These links and notes from Microsoft all indicate to me that support for all OS except Windows ME is dead, and even then Microsoft says to upgrade to latest version to make sure that you are protected and have current security updates.
IE 5.5 users *really* should upgrade their browser. They are vulnerable to security risks otherwise. (my blog-only added note: Better yet – switch to Firefox!!!)
[HUGE thanks to my better-half Sam for finding all that for me]