Here's a frightening little article I read today:
http://www.informit.com/articles/article.asp?p=174156
The first few pages are kinda yadayadayada - nothing new. Early in the article, it says that Firefox outperforms IE6 on every level, and just claims it is a fact, no justification. But the last page is just plain scary. According to the author, Microsoft is planning to use IE7 and Longhorn and .NET to take over the internet. All that will be left is dumb fansites, and photo galleries, like back in '95 when nothing was on the internet.
So in order to preserve the internet as a place where we have a free exchange of ideas, documents, and entertainment, you MUST use a W3C standards-compliant browser.
Personally, I think the idea of a Microsoft Network that controls the web is a baaaaaad idea, and I will fight to keep that from happening, even if it means I have to become independently wealthy in order to buy defection from MSN. MSN, that name means something new, now - a frontend to hell.