You DO have a MOD CHIP don't you? Why would you be trying to play games the NON MODCHIP WAY when you have a MOD CHIP. It's that simple. Please read up on the different methods of booting games on gamecube before spamming.
DM, dont suspect that everyone have mod-chip, i dont have neither. And to Tom's question... You need PSO1&2 version, not Plus. Best place i have found it is Huutonet, but i dont think you live in finland But look at Ebay, or local gamestores, or any web-auctions or samelike.