No, you do not. However, I'd caution you because I had some very negative events occur due to the upgrades (not on all machines I tried, but certainly on some, mainly dealing with security-related issues which had nothing to do with IE), so if you get some strange stuff all of a sudden - uninstall it via Add/Remove Programs in Control Panel and IE6 will then become active again. But if everything else works fine - use it, it's certainly much nicer than the old version on many levels. Of course, I still recommend Firefox to people, especially if IE7 fails to work correctly.