I have been using an old laptop as my firewall - running SL5
like all my other computers. 

I recently purchased an ALIX 2D3 single board computer ( designed
by PC Engines of Switzerland, http://www.pcengines.ch/alix2d3.htm 
and sold by netgate.com for $180 with case and power supply). 
The board has 3 ethernet ports ( WAN, LAN, DMZ ), 256MB of RAM,
and uses a 500MHz AMD Geode X86-compatible processor with
built-in AES crypto engine (for speeding up VPN links).  It uses
a Compact Flash card for "disk" though it also has a header that
can connect to a PATA hard drive.  No video display, though there
are USB connectors and a mini-PCI slot on the board where a 
display card can be added.

The board draws less than 4 watts operating.  So it is about 3X
faster than the old laptop, and 10x less power.  Some people are
setting these up with the OpenWRT distro, but that is optimized
for small flash footprint, and has too many bugs IMHO.  I tried
that for a few frustrating days, and gave up.

I attached the CF card to a USB adapter, attached that to a
diskless desktop computer, and installed from the SL5 DVD.  After
tweaking /etc/fstab , /boot/grub/menu.lst , and /etc/inittab for
a serial console and different drive names, the card booted fine
on the ALIX.  I made some flash-friendly changes (noatime, remote
logging, ramdisk /tmp, etc).  I also added a rc file to copy the
MAC address of my old WAN connection.  I am moving the config
files from the old firewall laptop now, and will deploy soon.

Which raises a question - is anybody else on this list interested
in my notes on how I am doing this?  I can put a write-up on my
wiki if so, otherwise I may forget some of what I did.

With SL5 driving massive computation clusters consuming megawatts
at the high end of the spectrum, it is nice to know that SL5 is
also useful at the low power end, too.

Keith

-- 
Keith Lofstrom          [log in to unmask]         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs