There is no doubt that free can lead to huge user bases and massive adoption. In the face of venture capital or existing cash stores, the siren call of free often sounds like a low-risk bet on future profits. In practice, free is a costly mistake that businesses and small developers should avoid, and users should run away from like the plague.
I believe a person’s PC is pretty much defined by the apps they utilise beyond the ones that come on it. Two years after the iPad’s debut it’s in that same position. A 16GB WiFI iPad with standard apps is as much “PC” as many people need. A “power user” gets more storage, possibly adds cellular and the Camera Connection Kit, and goes beyond the default apps to add software such as Writing Kit, GarageBand, iWork, Dropbox, Photogene, iThoughtsHD, etc. to meet their personal needs and interests.