The Mozilla.org site is currently taking a battering as millions of downloads are initiated, but ftp.mozilla.org seems to be faring better:
If you can use the torrent do so, but if you're less technically-inclined or on limited bandwidth just right-click and download the exe. If you have an older preview or pre-1.0 version of Firefox installed, I suggest exporting a copy of your bookmarks for peace of mind before installing. Uninstalling the previous version before installing 1.0 is recommended, but I didn't bother; just tweaked some values in about:config to carry over my extensions (all apart from SessionSaver took this okay.) At a guess, it'll be a day or so before update.mozilla.org is responsive enough to allow downloading extensions; like I said, millions of downloads will be battering the server.
With the release of 1.0, now is an excellent time to prod those family members and friends who think that the internet is a big blue 'e' icon to choose a browser that will make their time online safer and more productive. The Firefox developers have striven to provide an intuitive, clutter-free interface for beginners (whilst more confident users have the option to use a wide variety of powerful extensions if they wish.)
Reasons to choose Firefox/Mozilla:
As an additional note: remember, if someone is using web software such as the MSN Browser, Avant Browser, MYIE2/Maxthon, Crazybrowser or NetCaptor, they're still using Internet Explorer—all these programs do is layer a different interface on top. Pages are still displayed using the same insecure and vulnerable code, so try to avoid these shells.