Your DVD should already be region encoded for OZ (region 4), but it may have slipped past or maybe you bought it OS.
If you have Power DVD, right click on the screen and go to "configuration" then "information". That will tell which region it's set for.
If it's not 4 then try the Liteon site to get a region changer. You only need to change it once and in any event the player will only let you change it a limited number of times.
There is a way around region coding. If you rip the DVD to HD with something like CladDVD(provided you have enough space) and play it from there, region coding has no effect.
Region coding has nothing to do wih transmission format. The 3 systems in use are PAL (and derivatives) NTSC and SECAM.
So you can quite legitimately buy a region 4 disk in any of the formats. The big benefit is that most DVDROM players will play all formats and your PC doesn't care. But it's wise to stick to your own local system even though the best is PAL.
[This message has been edited by daylef (edited 11-21-2001).]