Everybody else was doing it.
This is where I do my bit to spread Firefox (makes it sound like a sandwich filling or a venereal disease). Details on exactly why Firefox is the bestest browser out there can be found at the Firefox homepage. However, if you don't want to read all that, I think this excerpt from an IM conversation I had with my sister should convince you:
13:16(13:07:52) Vhata: why didn't you like mozilla? 13:16 (13:08:05) Bex: It had a funny dinosaur icon And then later: 17:05 (17:04:09) Bex: I downloaded Mozilla Firefox 17:05 (17:04:16) Bex: it's good hey 17:05 (17:04:31) Bex: and it doesnt have a funny dinosaur icon