Speaking of which, if you want "always on" connectivity, but without the fan noise and power consumption of a full blown PC, then
these boxes may be just the trick.
I have one of them here (currently unused) and am considering using it as the Linux AP server/firewall. The whole set of required software will easily fit onto a single 128MB CompactFlash card, so no hard disk is required (but one could be used if I wanted).
[EDIT] One note though, the PCMCIA slot is 16-bit only on these boxes at present.
Cheers