There seems to be a lot of talk about a potential kill switch in Windows Vista, but that would be very good news for Linux and open source adoption in most of the world and perhaps even college campuses. The tighter the anti-piracy controls on Microsoft software is, the wider the adoption of Linux.
A person in China for example making $300 a month will save up and spend $400 on a computer. They will spend 100 Yuan (about $12) on home grown software but they will never spend $100 on software when they can buy a black market copy for $1. If that wasn't available or if Microsoft made it impossible to use the software because of WGA, they'll simply stop using Windows and stop using Microsoft Office and use Linux and Open Office. In Government agencies in the third world, this is often the case unless they're able to negotiate an extremely low price from Microsoft. Even Bill Gates admitted that people can't buy software until the economic standards are raised in the third world.
There is a similar dynamic with college students though not as extreme with American college students since they have a little more money. College students also have the academic versions of the software available to them but even that's a problem for some. Many college students will resort to copied software but when those same students graduate and join the work force and have money, they become loyal paying customers. If they can't copied software then they'll simply use free Linux and Open Source solutions and they'll continue to do so even when their economic status changes.
Microsoft has more or less always turned a blind eye towards individuals who use pirated Microsoft software though they'll implement a few hurdles to using it such as the lack of updates and patches or they'll turn off Aero functionality in Windows Vista. Is it possible Microsoft could suddenly harden their stance on unauthorized copies of Microsoft software? It certainly is, but it would be a great boon to Linux and Open Source.