Well component can carry progressive scan while composite can not. That helps alot for HDTVs. Also component can handle higher resolutions like 720p and even 1080p (in some cases) while composite can only do 480i.
Although, PS2 can only output 720x480. PS3/Xbox360 are a different story
Although, PS2 can only output 720x480. PS3/Xbox360 are a different story