Well if you don't, and something shorted and started a fire - your insurance'd be void. We have an annual fire and safety check every year, and to pass it, you'd be amazed at what you're supposed to do. All plugs should be switched off and removed from the sockets, and you can't even have candles standing around if they're not placed on a hard, imflammable surface! Providing you don't get cut off - i.e. by not paying your telephone line rental/ISP, there's no reason why your computer shouldn't work as soon as it's connected up again.