Kathi,
My husband bought a very small and compact sling back style backpack for his lap top, on the off occasion he needs to bring it home when he rides to work. Usually, he doesn't need to, but he did use it twice this past summer. Now, he hates riding with packs, so I may feel differently, but he said it was really heavy. And, his laptop is very small. I have an I Book, so it definitely is bigger. I might try it, though. I know I won't put the lap top in my pannier, after my heavy library book experience. I am not as nimble on the Jamis to begin with, as opposed to my road bike, and although I love it, I won't do anything else to upset my already precarious balance!