Dvd 600x

I have a Thinkpad 600X 2645-4EU with Windows XP. I installed a DVD-Rom drive but I can not watch DVDs. Whenever I use Windows media player, an error opens saying that there is a problem with the digital copy protection and tells me to update my video drivers. Well my video driver is at its highest version. I also installed Interactual player to see if it works. When I try it, it tells me to update my audio driver, which is also updated to its highest version. However, I do have a DVD decoder. I have looked everywhere for the Mediamatics DVDExpress software that originally came on that laptop and have not had and luck at all. So if anyone knows any program I can download that is compatible with not only Windows XP, but also with the older hardware drivers then it would be great.