Hardware wise (you will laugh), my killer Linux server is a P166 laptop with 64 meg of ram! It has a nice small form factor (sits on a shelf in the basement), built in battery backup, and for those very rare occasions I need local access, just open up the lid and away you go. Because its Linux, I dont have to have the GUI running. Plenty fast for a home server. I'm running Mandrake 8.0 distro. Main Apps I use on it are ProFTP, Apache web server, Samba file sharing.