codecs for playing certain DVDs

[woodie]

My daughter has a brand new Dell Inspiron 2650 laptop at school. It only has a DVD drive not CD writer and is running XP home. Before she left I checked it and it played a commercial DVD (Lord of the Rings) but did not play home made VCDs, at least it did not automatically play them on the DVD player that is installed. I have since discovered through a posting on this site that I can get Windows Media player 8 to play VCDs by opening the MPEGAV.Ext. She called me the other night to say it will not playb a DVD she just bought. It is saying I don't have a certain codec installed. I did install the Nimo codec pack which helped with AVI files in Media player. I don't know about the latest DVD but I have older Dell desktops at work and at home (both XP pro) which have no trouble with any DVD or home made VCD, it just comes right up in the installed DVD software (Win DVD). Has anyone experienced this? Why the difference? and what do I do to make her computer viewing easier. Thanks

[woodie]

Here is a new puzzling slant on this problem. Now when I use the DVD Player program it is saying that I need to lower the video resolution which I did and it played the DVD. I tried a different DVD and it told me to lower it again, but it only has two settings and it was at the lowest. Is it the video card ? It has 16 megs of video ram and plays Dvx avis full screen with no trouble. What gives?