it depends on the 5.1 receiver you have. It can be audio only or audio/video. As you say it has HDMI, it's probably the latter.
In this case, youYou have to plug the PS3 and the WDLive to your receiver, both in HDMI (providedas your receiver has twothree HDMI input)inputs, and connect the receiver HDMI output to your TV HDMI. You'll
You'll then choose your source (WDLive or PS3) on the receiver and the TV will always stay on the same HDMI video channel. HDMI carries both audio and video signals.
To see if this so there is feasibleno problem on this side, edit your question with brandreceiver being a A/V one, it will carry the video part to your TV and modeltake care of your 5.1 receiverthe sound output on the 6 speakers.