All of the images are 48 X 48 and you can download any of them by right clicking on the image and select 'save picture as' or 'save image as', etc.
You may notice that some of these images look familiar and most likely it is because most were used as icons. They are not useful in that format for the web so these are in the .png format. I think that having them look familiar, but as icons will help your site look very up to date.
BitTorrent Client 1
BitTorrent Client 2
BitTorrent Client 3