You need to develop or hookup a home theater PC to your receiver and connect the keyboard to the PC.

What digital music service will allow you to stream music from both your PC and compatible home theater audio devices?

You can find information about setting up a home theater PC online at websites such as TUAW, Appstorm, and Digital Trends. You can also find ideas for designs online at Gizmodo and Wikihow.

The ATI Theater device delivers TV signals to a PC using a specially designed chip to transfer the Digital Television signal to a PC in high definition.

Some ideal requirements for a PC to construct as a home theater is a smallish footprint, able to handle high definition resolution video, powerful enough to run what it needs to without having to run too many loud fans to cool.