I installed IE7 Beta2 about 30 minutes ago and I've been playing around with it. So far, so good. I had it crash one time on me while trying to do a forum search on myitforum.com but other than that it has been great. If everything continues to work well, I may end up scrapping FireFox at home. I can't live without tabbed browsing and IE7 seems to do a great job with them. I love how the tab groups work and the fact that they kept the same shortcut keys that FireFox has used (CTRL-T and CTRL-W to open/close tabs).
http://www.microsoft.com/windows/ie/ie7/ie7betaredirect.mspx