> I have looked high and low for the bottom end hardware requirements

Not _terribly_ low end, but let's start somewhere :-)...

I ran m0n0wall just fine on the low-end Soekris 5411 box for several weeks.
That Soekris was the 4511, http://www.soekris.com/net4511.htm, which is a
100MHz 486 with 32MB RAM. It fed from a 640/128k DSL and distributed to ~10
clients: - 2 wired, 8 wireless. Note that I never intentionally stressed
tested it with large LAN transfers.

Since then I've run on its big brother (sister?) the 4521 which is
133Mhz/64MB for months on end with no problems at all. (Longest time between
reboots was ~2 months due to upgrades / messing with other stuff).

Hope this helps.... michael