Vista will have a mechanism that requires internet connectivity for all PCs, and you get charged for each startup on a PC that's not the registered base hardware.
Okay, I just made that up. But what's sad is that such a rediculous notion is actually believable these days. There's a lot of power for content/software providers in how they control and allow use of their product, and it doesn't always make any sense for the customer or the public good in general. Yet, whenever any resistance comes or alternative legal structures are proposed, they cry that they are on the edge of poverty... "piracy, piracy!" If you give the customer an inch, they'll rob us blind and then no one will produce any content.
Okay, sorry about that rant. It's been a while since I railed against DRM and copyright law. I feel much better now.
Back on topic, I wouldn't be surprised in MS comes up with some sort of way to tie a license to a piece of hardware. But I'm not too worried.. they will tread lightly because the last thing they want to do is push everyone faster toward Linux.