If you are using the PS3 on your DVD input, then you can't use the dvd component for another device. Only one connection per input name is allowed regardless of what type.
Hook up the 360 to the cable inputs and make sure that component is selected for that input in the menu. Do the same for the wii but pick another input. (like VCR or aux).
A hookup diagram can be found
http://63.148.251.135/redirect_servi...800_EnQSS_.pdf