If all you have is the DVD and not the original iDVD projec, then your only choice is to insert the disk in, double click on the icon and open the Video TS folder. Then, you can use a program like MPEG Streamclip to open the VOB files and convert them to QT movies, which you can then drop into iMovie to slice up. Keep in mind that if your slide show was made in iMovie, as opposed to iDVD, you won't get the pics themselves, but frames from the QT file that iMovie converted the photos into, before sending it to iDVD. Hope this makes sense.

If it's saying you're missing the MPEG 2 component, then it means you need to buy the exta plug-in from Apple - I think it's about $20.00. If it's saying something else, you need to copy and paste it here, so I can try to help you.