^^ and the quality differences for SD through the composite vs. component output is going to depend on the quality of the upconverter of the box vs. the upconverter of the television
some cable boxes probably have great quality outputs with all definitions, and most boxes probably have defeatable upconverters, so you can utilize the same outputs, whether it be hdmi or component for all channels SD and HD with or without internal upconversion. this, of course, would require reading the users manual, however, which escapes most people