I left IE7 (da Elder Aunt with Lipstick) on my father-in-law's computer because he's on dial-up, and I didn't want him to deal with the upgrade and improvement downloads that Firefox frequently issues. Works just fine for his surfing. I have FF hidden and I use it to avoid the painful nature of IE.
For those wondering what this is all about, modern browser now all have Add-Ons, little programs to add functionality to the browser. IE has a handful (last time I looked) all created by Microsoft that don't do anything useful, while FF has 1,000s, here's a few of the 1 I use to make surfing life easier:
Select text and it's automatically copied to the clipboard.
Notifies you when you have mail in GMail
Google Browser Sync
Syncs Bookmarks/Favorites between my Laptop and my Desktop automatically
Download videos from YouTube, etc.
Tab Mix Plus
Makes tab browsing much more powerful
Makes tabs colorful, bringing joy to the world!