I am a fan of this HTPC software, as it runs on many platforms such as Linux, Windows, Mac and fairly recently they added iOS so you can run it on your iPad or v2 Apple TV (ATV2). Installing it is quite easy but requires a jailbroken iPad or ATV2 so if you don’t like that idea, stop reading before you upset yourself!
Why run XBMC? Well it is a good interface, highly customisable and integrates well with other apps. For example you can use Sickbeard to download TV shows and automatically add them to your XBMC library. Everything automatic.
But one requirement we have is to watch TV upstairs and downstairs so having a central library which records which shows you have watched and where you are in playback is a big help. Normally XBMC installations have their own libraries but a shared library is possible. I have my two ATV2s and my iPad all operating on the same shared library. Heaven! Some helpful guidance can be found here
With ATV2 XBMC there are further complications and differences from the standard shared library. Primarily you need to allow XBMC to generate the database and ideally you want your thumbnails stored on server too. A key performance tweak is to edit your MySQL INI file to disable name resolving (without this the system is unusable). There is also another major performance hack called Dirty Regions but I haven’t yet felt the need to try that. Sounds a bit dodgy doesn’t it? ;-)