ive had the component cables since the day they were released from nintendo. i have the nintendo brand myself, but ive seen other brands as well. they make a noticeable difference when running in 480p vs 480i. every time i go to someones house and i have to play in 480i, with the regular cables, i notice a big difference, esp on games like zelda and galaxy. imo, they are well worth it.
progressive scan is always going to be better and will always look better.
here are some pics to prove it: component is on the left and composite is on the right:
click to make the pics bigger.
the difference is clear in my opinion.