As part of my original requirements i wanted to be able to stream media to all devices within our home. to do this we used an awesome application called plex! a mate tells me it was originally for apple but has now been extended to android/pcs hooray for that!
the application consists of a server and a client install. in my setup the server install is on my htpc. setting up is really easy its just a case of install and adding your libraries. much like xbmc it has its on scrapers which will pick up information off the many online db's. the server service runs in the background and wireless device on your network is able to pick it up. now once the server is setup you simply download or install the client onto your device.
the great advantage of this is that all your transcoding is placed on your 'server' pc. this takes the load off your wireless device and also you dont have to worry about codecs as all the transcoding is done on your server. a brilliant piece of software!
alternatively you can use plex as your media centre software but i really like the feel of xbmc so im using both. xbmc for the htpc gui for the tv and plex for the wireless devices.