There is an easy way to setup wireless speakers you can control with your iphone.
It's a little expensive, so plan to do expansion of your network in steps.
The key components of the system are:
an iphone, iTouch or ipad
an airport Express (or more)
a wireless router
-an airport base station is recommended
an iTv
-a computer would work too, but the iTv has some features not on computers
-and it's cheaper