Saving a slide in a .pps presentation

Someone emailed me a .pps presentation and I want to save a few of the pictures/slides contained in it, but there doesn't seem to be any "obvious" way to do so. I want to save just a few select slides to use as wallpaper. How do I go about it??

You want to export the slides as PNG or JPG then. If you export the presentation as PDF then open it in Preview, you can do Save As and choose PNG or JPG or a variety of others to save as.

Thank you very much!