I guess I'm a little confused. I tried downloading most of the Keep at Shadowfell maps over the weekend. He had DPI info for the images (many were 72). The problem is, when i tried to print them in PosteRazor, they came out with the squares either way too big or way too small. In one case, my players had to use the small six sided dice to represent their characters (a different color for the monsters).

I can't set a DPI for my printer (or PPI). I have the GIMP available for printing as well. Is there some better detailed directions for how to print available?