XBMC is the most popular and the best option for DIY media center I think. But it doesn’t cover any smarthome areas except entertainment. Luckily XBMC provides plug-ins and scripts which allow en easy way to extend basic XBMC functionality. So, to add possibility to control X10 devices to your media center you may use either heyu + some scripts or plug-in X10 Commander Lights. Which one to use is up to you. The first way is more difficult but it’ll give you a full control and understanding the low-level logic while plug-in provides easy way way. Even for non-geeks. It’s always good when you have more then one way to do something.