You mean composite/interlaced vs. component/progressive? I ask because you must use component for progressive. Componenet is always interlaced. You'll see a big improvment just going from composite/interlaced to S-video/interlaced. If your TV is HDTV and is line-doubling your s-video or component/interlaced signal now, you may not see a big improvement by simply going to component/prgressive, especially if your TV has film detection (3:2 pulldown). Just try it and see.
well i am talking about my gamecube/xbox you know? i dont have the component cables yet for progressive scan for my hdtv yet. so i am using composite. so theres a huge difference i gather? especially since i have a high end tv correct?
Absolutely. Most of the xbox games are 480p, and some of them are 720p and 1080i, but all you're seeing at the moment is 480i (probably upconverted by your tv). You should notice a very significant difference when you purchase the High Definition AV Pack, and some component video cables. You'll also notice a nice improvement in the sound (Dolby Digital) if you have a 5.1 system (assuming you're using the standard av pack).
Yes, as above: you cannot get progressive scan using the composite cable (single yellow RCA connection).
More than this, you will find much better color and luminence separation with a component cable (three RCA connections: green, blue, and red) when compared to composite even apart from the benefits of progressive scan.
So you will notice a fairly significant improvement in picture quality for both your GC and XBOX when you switch to component cable.