If you are wanting to know what you need to play online and how much I can help you out.
Network Adaptor - $40
It doesn't cost anything to play online with PS2 except for buying the NA. The only thing that costs anything extra are a few MMORPG games. But for MK:D all you need is the Network adaptor and a broadband connection, and a PS2 of course

You will also need an eithernet cord to plug into the back of the PS2 unless you just take out of the back of your computer.

I have a wireless Broadband Router which gets hooked up to the cable modem. Then a wireless game adapter which plugs in with the PS2 adaptor, more expensive than just hooking the PS2 to the cablemodem.

thanks for the info i better go get one