I've been playing around with scrolling large backgrounds efficiently in games. I came up with a solution that seems to be working pretty well. It's not optimized yet, but it's working, and you'll get the point. Using this method, a person should be able to not have to worry about how big their background is, as only a piece of it is displayed at any time, and you don't even have to cut your background up into tiles.
Check out the demo here:
http://blueflamedev.com/blog/wp-content/uploads/2008/04/tilemaker.swf
You can read more about it if you want at this post:
http://blueflamedev.com/blog/?p=29
http://blueflamedev.com/blog
Blueflame Development and the Citrus Engine
Blueflame Development and the Citrus Engine
