AIX NAT vs. Debian Masq

["Mullins, Ron" <rmullins@DigiTerra-Inc.com>]

Hey,
I'm trying to take over the firewall of our company. I would like to deploy
a Linux masq'd gateway (which I have done before for another company) to
replace AIX version 4 with NAT. Could anyone give me some ideas as to how
these technologies compare? Are there any arguments that can be made to the
higherups in Linux's favor? Should I (*heresy*) stay with AIX? *me, dodges
lightning strike*

Basically, is anyone familiar with setting up both and the pluses and
minuses? Arguments will have to be good, as an entrenched familiarity with
current system. However our MSCE is making noise about NT as firewall. So
with all speed brethren...

Thanks in advance