I live on the edge. I have one tiny linux box, a Corel Netwinder, that is my firewall, mail server (in/out), NFS server, SAMBA server, print server, web server, DNS host/server for several domains, remote access host (SSH, VNC, ...), DHCP server, time server (and client from a Stratum-2 outside source), etc..
All in a box that's about the same physical size as an Empeg, and which uses about 50% more power than an Empeg.
But of course I DO have a spare on the shelf, just in case.
Very power-friendly: took very little to make it, takes very little to run it, and it'll be tiny in the landfill when it finally dies.
Cheers