Why won't my DVD drive work?

I switched my cd drive from my desktop to a dvd drive from another desktop that wasn't working. My desktop recognizes the dvd drive but when I try to play a music dvd it doesn't allow me, giving the message "Windows Media Player cannot play the DVD because a compatible decoder is not installed in your computer" . What is wrong here? I did reinstall Windows Home on the desktop that I use and I did also install all the updates including SP2. How can I correct this problem? As far as I know, the DVD drive was working perfectly on the other desktop before it broke.