This is a very common problem in the photo-lab business. There are a great deal of one hour printers out on the market that are completely Digital. Being able to take all camera cards, film, CD, and DVD media and make prints. Noristu, Fuji, and Agfa all make really high end machines.
But the digital world works in Screen resolution and the photo world works around 135mm film.
So haw is this going to merge.
Cameras like yours give you the option while the printing machine give the photo-lab person the option of cropping the image, fitting the whole image on the page (white edges will show), or image size (this will print pixel to pixel regardless of paper size)
The best advise I can give anyone when wanting prints from there digital card is to use the consumer terminals. So that you can preview your image and make sure the cropping occurs were you want it. remember it's all digital you don't have to loose any of your image.
By the way the digital world won and most camera will stick to the 4:3 ratio
Jason