Attached Link: http://www.cafepress.com/cp/info/help/help_image_sizes.aspx

This link is to a page by CafePress that gives you an idea on what size you should render for whatever print size you want to make. Also includes dpi. I do 11x17 prints so I use these as a guide and they work perfectly. It would also give you an idea what size your background image should be for your renders, too.

FlyByNight