Sometimes computers just don't want to play DVDs and Windows XP especially gives you an error saying something about "codec." I used to try and find the right "codecs" and that would take forever. Now I just use VLC open source video player.
What can VLC do?
1. Go to www.videolan.org
2. Click the "Download VLC" button.
3. Navigate to the area in which you would like to download the file, and then click the "Save" button.
4. If you are in Firefox or Google Chrome the download might end up at the bottom of your screen. If step 5 doesn't start automatically, click here to get the installation started.
5. Click the "Run" button.
6. Click the "Next" button.
7. Click "Next" again.
8. Click "Next" again or select and deselect options. I just leave it as the default.
9. Click the "Install" button.
10. The next thing you will see is a progress bar showing the install's progress.
11. Now if you left the settings alone, as you installed it, your DVDs should open up automatically. If it doesn't start up automatically, just go to your start menu and select "All Programs" and then find the VideoLan folder and select the "VLC Media Player" option.
12. Under the "Media" menu you can see all of the different options that you have to choose from to play the correct file type.