I don't think it'll make any difference. I have both component and S-video hook ups for SD (different TV inputs)--NO difference. SD pq on my 65" HDRP varies from ok to lousy depending on the channel. The pq on my SD CRT TV's is outstanding on all channels--certainly nothing like HD but excellent for SD, clear & sharp with great color. Go figure....................
I agree, it's very hard to watch anything in SD when you have to stretch it to fit your screen. My wife hates the black bars on the sides so we stretch everything... thank goodness I can pick up my locals OTA in digital.