Slightly OT question about network setup..

Hi all.. I've got a question for you if you feel the need to reply..
We're working on a house remodel and we're about a month
into the project (demo is all done and framing is coming soon).

Anyway, I'm planning on running CAT6 from almost all rooms
to a central location in the house where all wires converge for
connection to a multi-port switch (10/100Mbit for now, but will
eventually move to gigabit unless I can find a gigabit switch on
the cheap). Anyway, I'd like to move to a fully configurable
router/firewall setup over what I'm using now (an Apple Airport
Extreme) and am pondering my options. My specs for such
a beastie are below :

1) configurable firewall -- can allow ranges of ports to be unblocked
and can distinguish between TCP and UDP blocks -- something
that Apple really doesn't allow directly in addition to the usual
firewall featureset.
2) rack-mountable preferably
3) Not consume tons of power
4) Support wifi either directly or via something plugged into it.
5) web-based configuration (preferably)

Since I've got a Proliant 6400r sitting at home chugging along
as usual, I was thinking about using it as the firewall/router
in addition to it's current jobs running a web server, mail server
database server,etc. I'm concerned though that IF the firewall is
breached for some reason, that said "hacker" could damage
my files/photos,etc that sit on the same server.. Is this something
that I should be worried about and should I just get a separate box
to use as a firewall/router -- and do you have any suggestions for
something on the very cheap end of things.. Anyway, just thought
I'd ask you guys since I'm sure you've done this before.