Advanced Slide Show is a nice utility you can use to easily view a sequence of images as a slide show, each image being shown for some predetermined time before going on to the next.

It features: load up 43 major formats of images, view the slideshow with 126 transitional effects, preview the images while loading up the list, save and load file list which saves time and effort in preparing your list of images for show, and more.

You would not need to worry about different image dimensions or file type as Advanced Slide Show would resample the images on-the-fly prior to loading them up on screen. You will get perfectly centered images each time. Advanced Slide Show is simple to use and doesn't need a rocket scientist to master it.