As a lot of people have asked about what I've found regarding DVD region encoding, I'll share the information here.
Once again... unlocking your DVD region code so that it plays all regions is NOT ILLEGAL... there are no laws against changing your DVD firmware or unlocking your region code...
Also, I'm posting this becuase there are a lot of people out there like me that have moved to different countries and would like to enjoy the DVDs they purchase legally in other countries. If you don't travel or buy special edition DVDs (such as Anime or UK titles that are only avaiable in certain region codes) then don't worry about all this stuff. One of the reasons we have region codes is becuase not enough people bitch about it... but moving along...
Basically it's like this... the DVD player in your drive is either locked or region-free. The code for locked DVD players is RFC-2, and for Region-Free it is RFC-1. On top of the hardware lock, all software DVD players have a region lock as well--I believe that all players allow you to change your region 5 times. This means that on the 5th time you can no longer switch regions. ABSURD!!
Fixing this is a two step process, and will not work on some DVD players. The first step is to update the firmware on the DVD player so that it becomes RFC-1. Not all DVD players can be changed, although people are working on firmware updates all the time. Do a search on the internet to find your DVD and which firmware version it is using.
RFC firmware updates can be found easily on the web. I won't post links here, simply becuase people that don't need these updates don't have to bother with them... and I don't want to generate "rubberneck traffic... so look for them yourself if you need them. Don't ask the manufacturer of your DVD player--they have that license agreement thing so they won't get involved. The people that are writing the firmware updates are the same people that write the firmware in the first place, so they seem to know what they are doing.
I have an eMac with a Pioneer DVD, and at this time the model I have is NOT upgradable to RFC-1.

Hopefully someday there will be a firmware update I can use.
If you have an RFC-1 player or can upgrade, the second step is to get software that allows you to reset the 5 change limits on your Mac. At this time the only software for OSX is "Region X", which works with RFC-1 players to reset the switch code.
The only further advice is to make sure you follow the instructions to update your DVD firmware, otherwise you could damage the unit entirely. You must also accept that this fix is done at your own risk. But if you're able to find an update that works with your DVD by all means do so, because it is your right to watch the movies you've paid for on your own DVD player.