-- Internet Explorer 8 beta 2: 168 bugs identified

-- Firefox 3.1 beta 1: 207 bugs identified

-- Chrome 0.3.154.9: 297 bugs identified

Among those bugs, 101 were labeled as "showstoppers," or more serious flaws that warrant immediate attention. Firefox had the highest percentage of those, at 24 percent. Twelve percent of Chrome's bugs were deemed "showstoppers," while 9 percent of IE's received the designation.

As for overall usability, Firefox had the highest number of "excellent" ratings, followed by Chrome, then IE -- which did not receive a single "excellent" score. Firefox also came out on top in ratings for general preference.