Contrary to the assumptions of many of us, a lot of people are going to find Microsoft's Eiger offer compelling.
Eiger will be a version of Windows XP for "obsolete machines" -- obsolete in that they run operating systems Microsoft no longer supports.
Yes, such machines can run Ubuntu Linux, which is free. There are a host of Linux Live CDs that one can get. But the cost of software is just one small part of the equation here. There's also the cost of the home network manager's time.
I learned this firsthand recently when my daughter's 733 MHz Windows box was hit by a vicious adware attack. Conventional techniques didn't work. The adware used all the standard virus tricks -- loading itself into memory first, copying itself into restore directories -- which frustrated anti-spyware applications. If Microsoft could deliver an idiot-proof transparent solution for this, I realized, allowing her PC to run until she's grown and out of the house -- $150 wouldn't seem like so much.
I already hear your objections. Why trust the people who gave you the problem? Why spend money for something you can get free? Believing Microsoft on security is like buying a Clinton promise on celibacy.
What I'm saying is that, for many, this offer will prove compelling. There's money to be made here. Give me an equally-compelling open source alternative any teenager can use. People will pay for it, if it's idiot-proof, secure, and delivers value.