You can't play online with the netlink. It's direct dial ONLY. The only online disc made was the web browser. And before you ask no there is no known way of using it over the net with some fancy shamcy pc trickery.
Do you think there would be a noticable difference between the 14.4kbps Japanese Modem and the 28.8kbps US Modem during direct-dial games? I'd love to get a Japanese modem (you know, to keep colors consistant ;D) but I don't want the lower speed to affect gameplay.