I would suggest MS Paint. Paint is not a very powerfull piece of software but what it can do it does fairly easily. I did this process on many DVD cover last night.

1) Open image into MS Paint (right mouse click>open with>Paint)
2) Image>Attributes Write down how width and height (in pixels) of your current image.
3) Image>Strech and Skew
4) Under strech, put in values less than 100%. You will have to do some basic math to figure out what percentage you need to reduce the image by. (i.e. 46%)
5) Save as

After that you should be just fine using this image on a button or pannel. I hope this helps. I found many of my cover images on Netflix that worked well.

Brad