Firefox 2.0 will be officially out in a few hours, but the links to download it are already active. So:
Note that these will send you to a random FTP server with the official release, so hopefully you won’t be killing one particular server. I’m only linking to the British releases here – if you want the rest, go to mozilla.com and wait :-p .
If you’re a Brit, then once you’ve downloaded Firefox itself then download the British English spelling dictionary to enable spellchecking in web forms. Unfortunately it can’t be distributed with the browser itself due to licensing issues.