Can I display uncropped images in Wordpress Grid Plugin?

Hi all,
I'm afraid I'm a complete noob at all of this but I jumped ship from another e-commerce plugin because of the great support you seem to offer. I have installed the Marketpress Grid Plugin and have managed to get it up and running but I was wondering if there was a way to display the images in an uncropped fashion (not in thumbnail format). I realize that this means it's no longer a "grid" format but I'd like to display a variety of differently shaped products without having to condense them all down into uniform thumbnails. I realize this is probably not a project for somebody with basically no experience but if you have any suggestions I'd be very grateful. The site is: