Why you have reached this page...
Presumably you're reading this because you clicked on the upgrade notice. And you only saw the upgrade notice because... well... because your browser isn't very good.
Simply put, for the first years of the web all we had were browsers that weren't very good. So we built pages with a bunch of cheats in them to make them look good in the bad browsers. We knew that would catch up to us some day, and hoped we'd have proper browsers by then.
The day has come, and we do have better browsers. Trouble is, how to tell people using the older browsers that it's time to download the new version? This is how.
It's nothing personal. It's just now that we've got properly made browsers, we can build our pages correctly. But they won't look right on the old browsers, and we don't want to leave you behind.
So here's the link to the Web Standards Project's browser upgrade initiative. There'll be further details if you're curious, and links to a variety of good free browsers. Very likely the latest version of the browser you're using will be there as well.
If you're on a slow modem and don't want to be stuck downloading a new browser, many computer magazines come with a CD full of software. These usually include the latest browsers too.