But how do you do it? How-To Geek showed us in an 'Ask How-To Geek' post recently.
Simply open the presentation in PowerPoint 2007 or higher and re-save it in the format *.pptx if it isn't so already. Then rename it and change the extension to *.zip (I know it damages files usually, but this is going to work).
Now, if you open up the zipped file, you'll see all the media, neatly organized in folders. This includes the presentation's template, images used, audio, video and whatnot. Browse to ppt, media and you will find all the images and other media saved in there. Simply extract the files from the zipped folder and they will be perfectly normal.