I found this code to replace images upon hover
http://www.createblog.com/forums/index.php?showtopic=15520
which states that
Unfortunately, I found this code to be useless; although, admittedly, possibly due to my error. I'm not sure what the pixel values indicated represent. Is it the size of the original image, the original size of the replacing image, etc. Does anyone know how I can make this code work, or if there is another one which I can use?