We have tested and confirmed that WBI works with the following browsers:
Internet Explorer 6
Internet Explorer 7 - get it at http://www.microsoft.com/windows/ie/downloads/default.mspx
FireFox 2 - get it at http://www.mozilla.com/en-US/firefox/
Opera 9 - get it at http://www.opera.com/download/
Google Chrome - get it at http://www.google.com/chrome (released September 4th 2008)
Any of the other browsers are a good choice and each has different characteristics that make them worth trying out if you use WBI heavily.