I don't see why you wouldn't upgrade to IE8. I find it to be one of the best versions of IE to date.
There might be some circumstances where someone's software is incompatible with IE 8. I upgraded computers for the clinic last week and I was instructed not to install IE 8 because of a software conflict with some software that they install on their computers. I didn't ask what though. They did slip stream 7 in. I generally stay as far away from IE as possible. It disgusts me that MS integrated it so far into the OS that you can't not have it. I think that is in itself is a security vulnerability. I also don't like it when a website uses the proprietary code that can only be used in IE or when an application insists on opening it up.
![[Image: lovefirefox.gif]](http://worldsbestforum.1.forumer.com/html/emoticons/worldsbestforum/lovefirefox.gif)
Some people still use defaults. I'll bet a lot of XP users still have IE6.