[LennonCook]

Firefox seems slightly slower sometimes, but is infact faster. It waits for a few milliseconds (time is adjustable in about:config ) before it starts painting the page. This makes sure that it will have all of the information before it displays it, which makes it quite a bit faster because it's not trying to do too much at once.

Luke, the sites Firefox doesn't work on are sites which are poorly designed in the first place: they will work ONLY in IE, because they use functions that only IE supports, that Microsoft came up with, and often won't work with IE for other platforms (eg, IE Mac). Complain to the web masters, get them to fix their sites.
As for IE being a good enough browser, read this document - 22 pages of problems in IE. That's a lot.
And even with Service Pack 2, IE is NOT SECURE. Look at: http://secunia.com/product/11/ vs. http://secunia.com/product/3256/ . In case you don't know how to read what Secunia says, the most critical bug in a fully patched Internet Explorer, is alot worse than the most critical bug in fully patched Firefox.
And the popup blocker in SP2/third party popup blockers: why should you have to use them? Why should you have to use a third party program, or use a specific operating system and get a very big file, just to have functionality in IE that other browsers have had natively for years? Why should you need to run an anti virus program, numerous spyware stopping programs, and a firewall, just to protect yourself from one program?
IE is the only modern graphical browser which lacks native popup blocking, tabbed browsing, and standards compliance across all the platforms it runs on. There's only one other - Safari - which is so restrictive in the platforms it runs on (and I'm not sure if Safari works on non-Mac systems or not - it may well be less restrictive than IE). It is the only browser which is integrated so deeply into the operating system that it cannot be removed - meaning, any security holes in it are holes in Windows itself, because they are always there as long as Windows is on your computer. And there are alot of holes. It also doesn't help that IE has two functionalities - ActiveX and Active Scripting - which are there specifically to give a web page more control over your computer.
Why should we have to put up with all of these things? And why should anyone hang onto a dying product (stand alone IE is a thing of the past now: no more updates except in the form of operating system upgrades)? Get Firefox, or Safari, or Konquerer, or Nautipolis, or Opera, or Mozilla, or even Netscape. But don't hang onto IE, you'll only end up falling behind.