Hi Deb,
In addition to what Kevin mentioned above, a custom template can also be set to use original size images by inserting the proper image tags into that template.
On the Auctiva custom template editor, which can be reached by clicking the "Create(Custom Templates)" link under the "Listings" tab. All of our templates use the [DESCIRPTION_AND_IMAGES] tag to identify where the descirption and images will be placed within the template, which assumes the use of 400 x 300 images. In order to use original size images, one can instead use the [DESCRIPTION] tag to specify where the description is to appear, and then use the individual orioginal image tags to specify where the images are to appear. In order to create an original image tag, just select "Original Images" from the "Choose Image Type:" pull down menu, and create the tags by clicking the "Image 1", "Image 2", Image 3", etc. links above. These original image tags will appear in the template as [IMAGE1_ORG], [IMAGE2_ORG], [IMAGE3_ORG], etc.
I hope this information proves useful. If you have any further questions regarding this issue, please file a support request using the appropriate link on our help page:
http://www.auctiva.com/free_auction_software_help/help.aspx
-Mike