Your best bet on resolving yout error 603 would be to just call up your ISP and tell them that your having difficulties setting up your ps2 for online gaming, tell them what you have (i.e. a router, high speed modem, etc) and they will walk you through it.

That's what I did yesterday, I finally got tired of trying to get it set up, so I called up my ISP and had one of the troubleshooters there walk me through it. Apparently, all I needed to do was power down the PS2, pop out the ethernet cable out of my router from my modem, and into my ps2, than reset the modem, pop in the set up disc, than go to LAN settings, click automatic, and it assigned a new IP and everything worked. So if you want to save timem and your fed up with it, I suggest doing what I did.