Vob, bup and ifo files are of the dvd format. As alang said, you'll have to import them into WMM and then edit. Or you could use another "specialist" dvd video editing app.

Edit: Here's a guide that outlines the process and tools that can do this without importing/converting the dvd video files...http://www.videoforums.co.uk/guide-edit-vob-mpeg-48.htm It was the first link on googling "edit dvd",

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