I often use PowerPoint to produce collage images and jpegs of images with words over the top – which I then incorporate into videos for one thing, but have also used to print posters from.  However, the ‘save as’ jpeg option defaults to a lower resolution image than I would like, particularly if printing the collage.  It is of course possible to change this.  I have all my computers set to save as 300 dpi, but just got a new laptop with Windows 8 and MS Office 2010 loaded, so I had to remind myself how to do it.  The instructions I have followed before are here and I can vouch that they work a treat.