How Do I Prevent Lan Party Theft?
Firstly, you need public liability insurance for the event in case someone electrocutes themselves or trips on a case of bawls or something. Secondly, you need a guy on the door at all times to act as a security guard/receptionist. It doesn't have to be a professional, you can ask for volunteers to do a couple of shifts on the door, but they do need to know what to do in case of emergency and have a working phone. I suggest having two people on the door so it's less lonely and so there can be someone on the door at all times. Thirdly, use a very simple asset tagging system - everyone coming in gets a festival-style wristband marked with a number. Their computer and monitor get marked with a sticker bearing the same number. Anyone carrying hardware out of the venue gets their numbers checked - if any of their credentials are missing, the police get called. Make sure not to publicise the location of the event and only provide details to registered participants.