What I find most interesting here, is asking an interested party for the definition.
If you asked General Motors to define "automobile", you'd have gotten: 6-tons, 4WD, fully automatic personal vehicle with leather upholstery and all other creature comfort built-in and a cargo capacity of 3,000 lb.
If you ask a dictionary, "automobile" comes from "auto"-self, and mobile: "that moves by itself" - defining a vehicle (any vehicle) that produces its own energy to move. Traditionally, any 3- or 4-wheeled (or more) vehicle with an engine on an open road is an automobile (by opposition with a motorcycle, which needs a driver to be balanced, and with a train, which must run on a dedicated track).
As such, the 500 lb., two-stroke engine 4-speed manual shift Citroen 2CV (where 'creature comfort' was limited to electric rain sweepers on a later revision)) was also an automobile.
So, why bother asking Microsoft about the definition of a PC? For Microsoft, a PC is currently a quad-core with 4 Gb of RAM, a terabyte of HD space, a 40 Gflop graphics card and a HD-DVD (scratch that) Blu-Ray drive.
A netbook is a low-cost, handy portable computer geared towards using the Web (it has many connection types built-in: 3G, bluetooth, wifi, ethernet); the fact is that 'low cost' doesn't mean 'low performance': if that were the case, the iPhone, with its dedicated processors, would not cost $400 but more like $1200 (if the marketing costs overhead proportion stayed the same).