Richard M Stallman. Who? Read Wikipedia's entry here to get up to speed.
A recent report from PC World on his views of Open Source, Microsoft, Bill Gates' semi-retirement and free software movement. Read it here. Is this radical enough for you? How much and to what extent would you agree?
Personally, I would advise to read his views in its entirety (over 2 web pages) and form your own independent thought. Why?
"All the problems of the world could be settled easily if men were only willing to think. The trouble is that men very often resort to all sorts of devices in order not to think, because thinking is such hard work."
"Whenever an individual or a business decides that success has been attained, progress stops"
Thomas J. Watson Jr of IBM