Look under your ps2. It should have a label saying the model number (SCPH 70000 or something like it) on top of it you can only have 1 from these 3 -
1. NTSC/U
2. PAL
3. NTSC/J
labelled. Its its NTSC/U, get your online games AND network adapter from US ONLY! if its PAL, then from Europe, if its NTSC/J, then you have no cohice but to get it from Japan!