I have the Nintendo ones and play on a HDTV. The difference is amazing. I played Zelda and SMG both with and without the component and comp is definitely a big improvement.
Be aware that the VC games can have troubles (Push A+1+Z in the VC game menu to fix that) and that it VC games will look horrible. I always plug in my scart cable to play VC games.
Some GC games look way better (REmake) others unplayable (Eternal Darkness).







