No transparencey in .png or .gif images.

I can not seem to get a .gif or .png to display with a transparent background on my page. page I have tried to embed and upload the image directly into wordpress…both give same results. I am using the latest versions of firefox and IE…both show up the same. I can however, embed them into the themes info box in the right column but that seems like the only place i can get away with it. I have seen previous posts regarding .png images on old IE versions. does anyone know what’s going on with this??