I am seeking advice on the security aspects of the configuration of my home
system. I have 2 PC's, connected to the internet via a firewalled NAT
router. The main PC is an i386 P4 used for general computing, the second is
an older i386 P3 which I intend to dedicate to internet banking for maximum
security. I have installed OpenBSD on the P3 with just the xfce4 window
manager and the Mozilla Firefox browser. Both PC's have separate printers.

1: The P3 will only ever connect to bank websites, which I have to assume
are 'clean' (I might be able to disable scripting for some sites). However
malware may conceivably infect the main PC. Am I right in assuming I need to
run PF within OBSD on the P3 to protect against possible intrusion across
the LAN? Would this be enough? Also even within this minimal installation,
are there services which I could/should disable?

2: Space for the P3 is limited and I would like to remove its printer and
print bank statements across the LAN on the main PC (running Linux, or maybe
FreeBSD in future) using CUPS. Does this introduce security risks?

Any helpful comments would be much appreciated.

Russell