If you want movies and games I suggest either an Xbox 360 for streaming from your Media Center PC or simply wait a year or so. The 360 costs about what the other systems cost but also enables gaming for kids or yourself, media downloads through Xbox live and the media extender that syncs with your PC to stream (wirelessly with adapter) music, movies and pictures.
Samsung, sony and several other media giants have just decided on a wireless standard for TVs, Camcorders, game systems etc. Once this is implemented you will be able to wirelessly stream music, pictures, movies, tvshows from your PC or other handheld devices straight to any TV with this wireless built into them.