On top of its exhorbitant hardware requirements, Vista's license is the single biggest gripe for me. After I first installed it, I called Microsoft support and asked what happens if I upgrade my processor — would I need to buy another copy of Vista? The answer? Yes, I would.
Motherfrick that. The whole point of having a PC (over say, a Mac) is that since 1992 I've built my own machines and upgraded their components to extend their lives. I personally don't make enough money to barely afford a lot of software, and rather than steal it, this was enough to force me to consider GNU/Linux. If by merely updating your hardware's drivers (most major video drivers are updated monthly), Vista invalidates your Windows installation, then enough is enough. That's more intrusive than I ever bargained for when buying Vista, and moreover, it tells me I can no longer afford Windows computing.