i hate explorer, but i like it better than firefox. i prefer opera which has more features than firefox, and seems easier to use for me. maybe cause i use it for so long now.
check out IE7 beta 2, downloadable from MS website - has all of the raved about features of firefox mentioned above and improved tabbed browsing.
Still in a beta for now (on XP) and apparently only to be released mainstream for windows Vista / XP64, but the features are sweet and i'm enjoying using it, much better than Firefox which i was using before.
I have heard the the biggest advantage to Firefox is security. IE is supposedly ripe for invasion of viruses, adware, spyware and other serious intrusions.