I finally bit the DSLR bullet and bought a Canon XSi with a 18-200 zoom lens to replace my large-ish point and shoot. Does anyone have a tip how to protect it in the backpack without adding a lot of bulk and weight? Most camera bags like the Crumpler and Lowes are a not something that I want to add to my load. I also really don't want to wear it round my neck most of the time, and just wrapping it in some clothing is a bit impractical and probably not too effective.

I know, not exactly lightweight, but it takes really nice pictures.