have a vcd with a slideshow of jpeg files burnt with Nero. How can I convert those dat-files back to jpeg-format?

Not easy.

You would require an MPEG video tool , which can show you every frame by frame. Then you would take these ’ stills ’ and save them to jpeg.

Perhaps virtualdub can be of any help.

Thank`s for good advice:)

Or you could get a proggy like HyperSnap, which takes pictures of the screen itself, and also doubles up as an image editor.