If your TV has 2 HDMI inputs you don't need to even run the HDMI through the receiver. This saves you money on cables and reduces the chance of HDMI handshaking issues. Also, if your Comcast Digital cable is your only component video source it also does not need to be ran through the receiver, it can be directly connected to the TV. You can use the digital audio output of the comcast, blu-ray, and 360 as you described with the receiver. IMO, running all the video through your receiver is a waste of time and money and would have a higher risk of error in some way or another.
The only reason I could understand using HDMI on the receiver was if it was to get audio, but that receiver does not support audio over HDMI. Also, if you TV only has 1 HDMI input you should use the switching for HDMI, the component video switching is not needed as it's only one source.