FOAK - WinXP personal firewalls

I'm looking for a personal firewall that is so thoroughly, amazingly,
unbelievably user-transparent that they won't even have to know it's
installed.

It will just protect them from themselves.

It's for a pool laptop which will be wandering between the office network
(non-domain machine) and client sites. It'll need to use various wireless
and probably occasionally wired networks for internet access, possibly
printing, and without any of the usual "Oooh, I've not been here before,
is this home/work/public?" dialogues.

Thoughts? Preferences? Avoid-like-somebody-else's?

 

XP's got one built in. Why complicate matters?

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".

 

The built-in one.