building a small/cheap/quiet firewall box. advice?

hi all.

i currently have a linksys wrt54gs + sveasoft talisman firmware serving as my gateway/firewall box connected via a static 3M/512K DSL PPPoE link.

time to upgrade.

i want to build/buy a box for a dedicated *BSD/Linux firewall.

on the software side, i'm considering m0n0wall, smoothwall & ipcop, and/or roll-my-own; i'm leaning towards m0n0wall (depends on PPPoE MTU Support; assignable both on LAN/WAN?) or i'll roll-my-own.

i've been looking at Hardware solutions incl. Soekris, WRAP, CappucinoPC, etc.

all seem nice, but each have some gotchas as well, and the $$$ adds up quickly.

so, i'm thinkin' ... gotta be a better way.

i'd *like* the box to be:

headless
small
quiet
1 WAN port
2 LAN ports (>= 100bT)
"power" >= 266MHz PIII <-- that's just a minimum
>= 256K RAM
enuf HD for a barebones distro
serial/USB is just 'nice to have' ...

all for under $300. buy or build, i frankly don't care.

i've been looking, and can't find the solution out there ... especially for the price. lots of topics *here* that address the bits-n-pieces ... but not quite the combo i'm looking for.

does it exist? or, am i dreamin'?

thoughts/comments/suggestions all appreciated!

thx all!

richard