Gizmodo have a look at reviews of IE7 and Firefox 2

and his conclusion….


Conclusion

“The new Internet Explorer is a solid upgrade, but it’s
disappointing that after five years, the best Microsoft could do was to
mostly catch up to smaller competitors.”
“Of the two rivals, Firefox remains the better application.”
– I plan on running Firefox 2, but I own a Mac.

Frankenfight: IE7 Vs. Firefox 2 – Gizmodo