Startup Idea : bulletin board layout designer

Have you ever had to layout a large number of pictures, posters, printouts, etc. on a bulletin board at work? I recently had to nail the following on a 4 X 8 foot board: 2 rows of 7 pictures frames on bottom, 1 row of 4 picture frames above that, 1 larger picture frame above those, and a small poster at top. All had to be evenly spaced horizontally and vertically. I do something similar several times a year. What I want is a simplified design program that will evenly distribute any sizes of rectangles similar to this, and give me all needed measurements to locate where I need to put the nails or screws. It should not be a bloated CAD or drawing program that tries to do everything and takes weeks to learn. Ideally, all features of the program should be learnable in less than 10 minutes. Output could either be by screen grab or PDF.