PS2 cable good for a PS3?

ok, so i took me ps3 down 2 me friend's place cuz his broke. I used his hdmi cable and internet and we played on it for a while. now i am trying 2 reconnect it 2 me tv and the ps3 turns on and lites up like it is suppose 2 but i am not seeing and vidoe or hearing audio on my tv. i have done wat the manual has said 2 do and it hasnt wrk. so i plugged in my old ps2 av cable into my ps3 and it works great. But is this a good and permeant idea? and help with any of this would be great!! (its a slim ps3)