I got a few computers at home. The two main ones that I use daily one is P4-3.2 Ghz machine that runs on Windows XP (I assembled myself) and a DELL PowerEdge 600C server that runs on RedHat 9 Linux. The Windows machine is my everyday workstation and the Linux box is my development server. I have an entire LAMP environment set up on there, as well as a CVS Server and I also use it for backup of my production servers (It has about 250Gb HDD).

The other computers you see in the picture below are not used for everyday use, but from time to time, its good to have a backup of backup and do safe experimenting on machines you wont care losing much if things go wrong :) Backups are never enough. All the computers are accesible through a 4 port KVM switch that allows me to use the same keyboard, mouse and monitor for all computers. On my main windows machine only, I have a dual head Matrox video card to allow me to use two monitors from the same PC as well as a TV and FM Card to allow me to play TV on my PC and listen to FM Radio.

All these computers are protected from the world by an external firewall. The world only accesses the open public  ports thru a dyndns domain. Each of them is connected to each other thru an internal LAN.