Finally got a hold of the VIA mini-itx motherboard/cpu I was lusting after a while back - picked it up with a nice little black case from www.idot.com for $170. Stuck in a DIMM and a harddisk, and it was all set to go (video/ethernet/sound all included on the motherboard). Gonna make a little personal server/firewall/NAT box out of it.
The nice thing about it is that the HD is the *only* moving part in the whole works. No CPU fan, there was a case fan, but it doesn't seem necessary so I unplugged it. Power supply is an external transformer brick, with no fan. Very very quiet.
Loaded FreeBSD 4.6-Release on it - seems to work pretty well.
Only problem is that I needed another ethernet port (being a firewall and all), but the case is too small to use the single PCI slot, so I'm using a Linksys USB-Ethernet adapter. It's supported with the "aue" driver, but there are some glitches: it hangs on boot if the Linksys is plugged in (on dhclient I think). Plugging in after boot works better. And if it's plugged in during shutdown it panics after syncing the disks. It's not a real disaster since I'll leave it on all the time, but I'd feel a lot better if I knew it could make it through an unattended reboot - if the power goes out or something.