Microsoft Genuine Disadvantage
Here's the proof, should anyone still need it, that choosing Microsoft is really very silly. There's nothing particularly wrong with Microsoft wanting to check the validity of a licence when you install their software - it could, if implemented right, prevent people from, say, installing the same licenced copy of Windows on several machines at once. However, allowing Microsoft to arbitrarily decide later on that a perfectly legitimate install is really pirated is Just Wrong. Worse, relying on them running their licence checking servers for ever is Just Plain Stupid. There's no way that they'll still be running in ten or twenty years time. But I guarantee that there will be people wanting to still run XP or Vista then, just as there are people running Windows NT, Windows 95 and DOS right now.
Given that, I fail to see how anyone who freely chooses Microsoft software can be anything other than ignorant, stupid, or malicious. Of course, most people who make that choice make it out of mere ignorance, as they're not used to thinking about how software security systems can fail. There's nothing wrong with ignorance. It can be corrected.