My Inspiron 8200 has a fixed 8x DVD drive, but video playback has always been slow.  Playback starts off smoothly, but it then starts to bog down, and the audio begins to break down as well.  The total effect is kind of like watching movies in jerky slow motion.  I have a GeForce 4 440 Go 64Mb with Nvidia driver version 4.2.5.8  My system is a Pentium 4M 1.6 Ghz with 512 ram and a 30 gig hard drive, which is only around half full.  I use Intervideo Win Dvd for DVD playback, but the problem occurs with other DVD players too.  My Norton virus definitions are current, and virus scans indicate that my system is clean.  I also shut down all other programs while watching DVDs, but playback is still slow.