OK, caveat first. This is not freeware in the classic sense. It is more like trialware. The...

Internet Explorer 6 Application Compatibility VPC Image

...is a virtual appliance available free from Microsoft. In this case, this virtual appliance consists of a pre-packaged fully patched Windows XP operating system that expires on March 30, 2007 and Internet Explorer 6. The appliance requires either the free Microsoft Virtual PC 2004 (released) or Microsoft Virtual PC 2007 (Beta and also free).

This appliance lets you upgrade your host PC running either Vista or Windows XP to Internet Explorer 7 while providing a fully functional and sandboxed IE6 for testing (at least until March 30, 2007). This is a great benefit to web designers and others needed to test IE6/IE7 compatibility without maintaining two physical machines (or buying an additional XP license).