Not sure how many I have, but it's at least five.
1. Main rig, 'Sathanas'. Primary system with one or two screens depending on availability.
2. Server, 'Shiva'. Only has four cables plugged in: power, keyboard, and two UTP patch. Operates as Apache, DHCP, DNS and PXE server.
3. Secondary, 'Cain'. Used for LAN parties. Not as powerful as Sathanas but gets the cast-offs, making it a beast in its own right. When active at home (usually for testing network apps), it steals a screen from Sathanas.
4. LAN server, 'Abel'. In the same ATX case as Cain, which has a built-in KVM and some homebrew power supplies. Used as a dedicated server at LANs.
5. Tablet PC, 'Seraphim'. Mainly used at work, but it is mine.
6. Hangar Queen, 'Lucifer'. The original secondary machine but now a source of spare parts. I'm going to fix it up and donate it to the Uni's Computer Games Society as a dedicated server. I'll not be able to get rid of it any other way.
So I have six. Only three get any regular use though.