Well,
It all really depends. Microsoft IE has some good points, FireFox has some good points. (I'm being impartial here, remember. I KNOW that IE is horrible, have changed my browser, so don't say that I support IE.)
Well, here are the bad points of FF:
>> FF crashes when you load too many tabs
>> FF has a LONG startup time.
>> It takes even longer to start when you install add-ons.
>> It also hangs, maybe even crashes your computer if you have too many.
Here are the good points of IE:
>> It comes built in the system, so you can download other browsers.
>> It has a quicker startup time than FF
>> It has Accelerators.
>> The upcoming IE 9 will have GPU - rendering support.
But, again, here are the bad points:
>> It's rendering engine is a ***bit*** more than crap.
>> You can't customize it.
>> It is known for sometimes conflicting with other programs.
>> The IE 9 will not be compatible for XP.
>> It failed the Acid3 test.
So, here's a final note: It's entirely your choice. You can choose the Trident engine of Internet Explorer, or you can stick to FireFox's Gecko engine, or you can see the other alternatives on the free market:
>> Avant Web Browser
>> Maxthon 1.67 (Classic)
>> Maxthon 2.5 (Standard)
>> Maxthon 3 (Much cleaner than Maxthon 2.5)**
>> Opera
>> Cometbird (Again, this is built on the base of FireFox, but with a faster load time)
>> Google Chrome
>> Flock
>> Netscape (Out of business)
>> Seamonkey (Gecko Engine)
>> Sleipneir
>> Lunascape
>> Konqueror
>> Safari
>> Wyzo
So, if you like FF, stick to it. No one can force you to use IE or FF, but if you want my opinion, I think Maxthon 3.0.8.17 is the best. (I'm not forcing you to download it; it's your choice, but, let me tell you, you're missing out on a lot :)
**Note that Maxthon 3 is in the developmental stage and is an alpha, for testing purposes only.