I have Firefox and would delete IE say for one reason: certain websites are built with IE and IE only in mind. This of course is not Mozilla's fault. Otherwise, IMO Firefox loads pages and images more efficiently, has a better user interface, blocks spyware/adware (AdAware finds almost never finds anything in my cache anymore), has a better "Find word in page" feature, has an "undo" button under "edit" in case you delete something you're typing (IE doesn't), and has a better pop-up blocker (SP2 IE has one but it pops up a reminder which is just as annoying as the pop ups themselves). There's no law that says you can't have more than one web browser. Download it, I think you'll like it.