Yeah, HDMI is better than S-video and composite cables for Television sets, but with the computer screen you set the resolution.
Resolution have nothing to do with signal quality... digital is digital, 1's and 0's ....the other are analog signals like VGA,Component(YPbPr),Full Scart(21pins RGB),S-video,Composite,RF(Pretty much quality in that order). Digital is far better than analog in giving the correct signal and very resistant to interference.