firefox and thunderbird on freebsd 5.3

[cmc2slack-freebsd at yahoo.com]

Hi, I'm planning on installing a new box (well
new to me, it's a PIII :-)) with FreeBSD 5.3
when it comes out in October. How much work is
it getting the Linux versions of Firefox and
Thunderbird to run on 5.3 or 5.2? Have you folks
had any problems with it? Will the newest versions
work?

I've been running 4.8 on a little P166 which is
fine for reading mail with Emacs but very slow
when it comes to browsing, will be nice to have
a faster FreeBSD box and be able to use Mozilla.

Thanks for any advice,