That receiver should take both audio and video over HDMI, so as long as your sources are outputting over HDMI, it should be good to go. You'll also want to use HDMI for things like Dolby TrueHD and DTS-HD, which optical can't handle (although optical will do plain old Dolby Digital and DTS.)
PS3 and HD-DVD player should definitely output over HDMI. Cable box, I'm not as sure about.
Don't believe everything on the Interwebz! A duck's quack DOES echo!