Yeah, It was built from the ground up instead of Internet explorer which keeps adding on to previous versions leaving holes for malware to exploit. Most programmers of malware don't know how to exploit firefox, not to mention if there is a hole firefox has so many people working on it itll get fixes fast.
And To add on to what jac said, It loads webpages more quickly as well, Since its a straight forward program it only has so many tasks to fulfill, Internet Explorer is built in to a windows system and has so many programs accessing it at once it slows it down.
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To Elmonomalo: Yes, Open Source is the best, Thats Why I prefer linux to Windows. I normally use Gentoo, But ever since I switched to this PC I havent been allowed to install linux
Reason Open source is good is because You can edit the actual code to get it how you want it instead of Microsofts view of "Less options, less chances for the user to f*** up"
If you ask me, I like to f*** up every once in a while when Im editting things around. lol Its a learning experience
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To Tommy Boy: I got the theme for Firefox here
https://addons.mozilla.org/themes/moreinfo.php?application=firefox&id=101
and If you were talking about the Title Bar I can give you the file for it, Supposing you have XP. (I got it from themexp.org, But it comes in an exe format that installs those pesky little toolbars in IE)
Oh Thats another reason Firefox is good, It doesnt have those annoying toolbars that IE has lol