[[MM]IKKE]

If you go to paint (in Win7 at least, might work on vista as well), you've got a button 'change format' in the main 'start' tab, under 'picture'. The only button I found to resize an image without keeping the old rates (I don't really have any pic editing programs). Paint is free, unlike photoshop.

PS my translations of the buttons might be incorrect, my paint and OS are in dutch, I translated the buttons.