how to split big map into several printed pages

I do use the following feature in Picasa (see link)
you can split your map in chucks of diff sizes 10x15, 20+
with overlap feature (this will help to easy link printed chunks of your map)

http://freegeographytools.com/2007/printing-large-maps-on-a-small-printer

"excellent free image organizer and editor Picasa has the ability to chop up a graphic into segments that can then be printed as individual pages and re-assembled as a poster. Select the image, then choose Create => Make a Poster from the menu"