Yes.  In Photoshop, it's a piece of cake.  Load up the image and then in the 'image' menu - select 'image size'.  Change the size from here - the image can't be wider than 800 pixels or higher than 600 pixels.  Or.  I stuck a quick and mostly user friendly program here on the site - called Lview - that will do the job as well.  Click here to download it.   It's an older version of the program before a lot of "features" were added to it.  Just download it, unzip it, and put it in any directory you'd like.  Run the program by double clicking on the lview icon.  Load your image and under the 'edit' menu select resize.  Resize the image there and then save the newly sized image.

Cool?

Dan

Thanks Kevin and Kravitz.