I imagine you mean portable mp3 players.
Just check with the manufacturer, the only issue would be with the AC power you would be connecting to. As far as the computers go, your mp3 players should work with any that will run the software. As far as AC power goes, Radio Shack has converters that can adapt from whatever power (and plug shape) they have in New Zealand to whatever power you need for your players. Or you can probably just run them off of their batteries.
So the short answer is yes, they will work.
Edit: I see in your profile that you live in Houston. I moved from there about 1-1/2 years ago, it's way, way, too hot there for me! I lived out in Cypress for about 5 years.