You can already play online with PS2. If you have a cable modem all you need is an ethernet adapter or something for like $40 at best buy and if not it will run you a little more. The modem Sony is putting out will prolly be cheaper.
XBOX vs PS2 Ive had a PS2 since launch and its sweet. Ive never really been a gamer until PS2 came out, it seriously made me like games more. Sony has a good history for developing good games, not just good looking games. Soon PS2 graphics will begin to look better when programmers start to learn the code better. Im not a fanboy of PS2 so Im not gonna be really biased but Im just not feelin XBOX. Most ppls feelings are that XBOX is not gonna live up to the hype and PS2 will still be king even after gamecube debuts. Check out the release calendar for XBOX games and PS2 and see what you like better. For me graphics do not make me buy systems, games do, and the 3 new systems all have excellent graphics, so which one you pick will not be like PS1 vs Dreamcast. For me I feel systems have reached a good enough standard of graphics so it will be fun on either system.