You have to understand that the soundbar takes the place of an AV receiver, but the AV receiver is designed to be a switch, while the soundbar is not. This is the heart of the problem. HDMI switching and splitting is an active process - any device that does it is powered and has microprocessors in it. Running two displays is not an entry-level feature.
Normally, as RTROSE was alluding to, each of your sources would connect to an AVR. You would use the AVR to select which device's video feed you wanted to send out (by selecting the input for that source), and the AVR would send out that video to the display on it's (typically) single HDMI or other video output, meanwhile it would process and amplify the sound for playback in separate loudspeakers. Your soundbar is capable of doing that for for only a few sources - the 1 HDMI, the 1 optical, and the 1 stereo analog (then there's the USB, which is useless in this scenario). You could connect your Blu-ray player or PS3 via HDMI, then the XBox via optical (if it has that?) and the Wii via stereo analog. Skip the DVD player, because you don't have enough inputs, and its function is made redundant by the Blu-ray player or PS3.
At that point you have all your playback options fed into your soundbar, and you just have to decide how you want to manage the single video output - the HDMI out. You could route two HDMI cables to the soundbar - one for the PJ and one for the TV, and then you would have to reach back there and swap cables when you swap displays. I wouldn't recommend this in general, because it is untidy, a hassle, and will wear out the port or the cables as you unplug them all the time. The other option is a HDMI splitter or switch. It often comes with a remote (and could be programmed to a universal, I expect) but needs a power outlet and will require an extra cable. So you run one HDMI cable from the soundbar output to the switch, and then two more cables - one to each display. You can get a switch for as little as about $12. http://www.monoprice.com/products/product.asp?c_id=101&cp_id=10110&cs_id=1011001&p_id=8150&seq=1&format=2