You can use your own internet service to play any PS2 game online. It dosen\'t matter who you go through.. you\'re still connecting to the same servers. Sega only had Seganet to reduce lag because it connected directly to the server and didn\'t have to ping offa most of the computers in the free world to get to where it was going.
Not that you\'re going to have to worry much about that anyhow since you have broadband.
Dunno if Sony is going to charge a monthy fee for using their servers.. but I wouldn\'t be surprised if they did. It\'ll be low.. like 5-10 a month. Plus you have to pay for certain online games like Final Fantasy XI. For most stuff like fps, racers, fighters, ect.. you\'ll probably just have to pay one base fee to access all of them. FFXI is a MMORPG and needs constant updating, patching, maintinence, and such.. that\'s why it\'s going to cost extra.