Online play with a PS2

I own an old version of the PS2 (PAL, unchipped) right now and I'm not playing any online games. It's getting old and I'm thinking of buying the slim version and get into online gaming, but I have a concern. How does it work if I buy a PAL console and have it chipped/modded so I can play the US and Japan only titles? I mean, US and Japan works at 60 Hz and PAL at 50 Hz. Can I still play with people in the US?

I was thinking of buying a JAP or US system instead, but then again I'm not sure if it will work with swedish broadband connection?

Which alternative would be better?

I'm not sure if it's like XB live, but i'm pretty sure if u have a chip in your PS2 it won't let you play online regardless of region.

So if I want to play for example MotW online for PS2 I need a US or JAP console?