Which free firewall uses least memory?

Hiya,

I've just bought a cheap backup machine (P3, 866MHz, XP Pro) which
currently only has 128MB of RAM but I'm getting another 128 in the
next few days.

Initially I want to connect this machine to my main one using a
crossover cable but I also want it to connect to the internet should
my main machine go down.

I have AOL supplied McAfee Firewall on my main machine & I'm gonna try
and install it on the other. If this doesn't work, could anyone tell
me which freeware firewall uses the least memory/resources cos of the
fact that the second machine will only have 256 MB of RAM - until I
win the lottery of course, then I'll go mad & upgrade it to 384 MB.

-- 
John Latter
Model of an Internal Evolutionary Mechanism (based on an extension to homeostasis) linking Stationary-Phase Mutations to the Baldwin Effect.
http://members.aol.com/jorolat/TEM.html
'Where Darwin meets Lamarck?' Discussion Egroup
http://groups.yahoo.com/group/evomech