Apples and oranges. I have a laptop for that kind of stuff but still carry a Newton MP2000 with me on a daily basis. Small enough to be pocketable and still big enough to be useful. The extended battery life (30 hours) makes it truly portable in that you can use it heavily all week on a single set of AAs, which are no trouble to replace if you do happen to run low.
90% of the time the principal use is to makes notes. The ability to sketch quick diagrams etc make the Newt much less distracting in use than a regular PC. Standard office type stuff, email, telnet and basic web browing are all perfectly doable too, although the platform is showing its age a little now.