For those of you using Windows that have the lame excuse that it's not your computer/you're not allowed to install software because someone else said so/blah blah blah:

Introducing:

<b>Portable Firefox</b>

It doesn't "install" like normal software, just unpacks itself somewhere (probably somewhere you can hide it ) and you can run it Usually better for portable devices, but I find it's just as great on machines you're not able to install on because you're not admin, such as at work