Today I received Internet Explorer 7 as part of the Windows update. For a professional webmaster this is a significant date, because it means that the majority of visitors (43% for this blog, ~60/65% for the corporate pages under my control) is now in the process of switching from IE6 to IE7. This should make a lot of things easier, but requires some legwork to go and check all sites if they work correctly.
Unfortunately, there are still people out there who continue to use IE6 or even have IE5.5 or older installed. The good news is that there are some smart folks out there who created monolithic, standalone archives of older IE versions which you can install parallel to your IE7. Check those links: