Our experience so far
We have installed IE7 in our workplace, and so far the users have had very few problems. A few things i have noticed: 1. Finally they added a 'shrink to fit' option for printing, which for oddly sized pages helps a lot 2. Unfortunately this same option causes problems when printing some emails out of outlook and outlook express(outlook uses IE print settings). The problem is related to some headers on html messages making IE7 think that it is a very wide image, so it prints all the text REALLY small. 3. Very few of our users actually take advantage of the tabbed browsing (though me and the other IT guys love it) 4. During installation the software does require windows genuine validation. So techincally 'yes' you do need a valid version of windows to run it, but of course there are ways around everything (I managed to install it on my home computer) 5. You cannot have multiple version of IE installed without using emulation software (i haven't tested what it would take to get multiple versions installed, but have read that it can be a bit of a pain without emulation). 6. The first question every user we have asked was 'Why did my favorites get deleted?' because IE7 hides the menu bar by default and gives you a star icon for your favorites. All in all we are pretty happy with it, and it is supposedly way more secure than IE6 was.