okay, not to drag this out, but I just thought of something, are you sure they want your image to be 300ppi and that 300dpi is not just the printing technology. If the image is to be printed digitally (i.e. not photographed) then anything above 200-250ppi is usually waste for just about any (digital) technology. If the image is going to be printed then photographed then 300ppi is usually required. Just wouldn't want you to waste rendering time.... I know there are some people itching to argue with me so I use the very well written article (not by me) linked above as my rebuttal :)