Does anyone know of any good software for managing multiple monitors. I have my MBP hooked up to my external Monitor through an HDMI switch. If I change the source of the switch eg to my PS3 then it loses the monitor connection (as if the cable is unpluged) and all windows revert to the MBP's screen.

I want to make sure any windows open and stay on the external screen only. If I turn the MBP on and close the lid so only the external monitor is active it works OK until I change inputs on the HDMI switch and then it instantly goes to sleep no matter what the MBP is doing, eg using the network etc. Sleep is disabled in the settings panel.