Dude, cool calendar!
Here is a suggestion: Instead of making it a BMP, you can make it a JPG.
Use a program like "Fighting Birds of World War II" a Smithsonian Institution Screen Saver & Wallpaper for Windows program, by Second Nature Software Inc.
I found this jewel at Egghead software for under $15. What it does is brings up the JPG, coverts it to BMP and loads it into your desktop. I have 50 plus jpgs of A/C and am only using under 3 megs! It has mass settings and you can set up rotating wall paper and use your calendar as a screenscaver.
I have scraped all the pic's that came with it, some were lame. (most of mine are 51's)
FYI
Mr.ED
Pony Driver
Knight