If you have a newly installed IE7 (not company preinstalled), or reverting back from a beta IE8 install. You will have an annoying redirect to this URL (http://runonce.msn.com/runonce2.aspx) every time you time open IE, regardless of what your homepage is setup as. First it foes to this page: (http://go.microsoft.com/fwlink/?linkid=54834 –) and redirects itself to the [...]

Browser wars never end and Acid2 test is considered the ultimate yardstick for web standard compliance.
Here is some history and background of Acid2 test from wikipedia:

Acid2 is a test suite published and promoted by the Web Standards Project to identify web page rendering flaws in browsers and authoring tools. Acid2 was released on April 12, [...]

In it’s own words Microsoft promotes IE8 for “professionals as well as those trying CSS and scripting for the first time.“, because of it’s built in tools for debugging purpose. ReadWriteWeb has done a great job promoting IE8, this is what they had to say regarding it’s standard compliance:

There were hints that IE8 would be [...]