If you currently have AOL, don't sign up with the PS2, just use the PS2 to log in to aol as you do on your computer(if you can).
I guess what I am saying is that if you can avoid any extra charges for the PS2 try to go that route. If yu can IN anway get indepent of AOL for your PS2, do it.
If you already have dial-up(non aol), and you can use that to get on the internet with the PS2, do it!
AOL is a sub-net. Meaning that when you dial into AOL you're not dialing into the internet. You will be dialing into AOL, and their network, then reaching out from there.
This will increase ping times, and make online play terrible.
Use your exsisting account if you can. The ping times (how fast computers talk) will be faster and cleaner. Making gamelay smoother.
It will most likely be cheaper.
If you want some pointers in making your exsisting connection the best it can be, send me a PM. I wrote an article in 98 or 99, on making the most of your dial up connection, reducing ping times, and getting a good clean connections for online gaming.