I don't mind that Vista's probably more aware of the machine on which it runs than any of the previous versions of Windows. My complaint is that the UI team decided that it must notify me of every last thing going on, no matter how insignificant. For instance, a little notification that says “Information: A jack has been plugged in” appears when I plug my headphones into the headphone jack:
I knew that, buddy. After all, I plugged it in.
To be consistent, the UI team made sure that there was a message appears when you decide to unplug your headphones: the “Information: A jack has been unplougged” notice…
I've only done some cursory Googling, but I can't seem to find any written design rationale behind such a notification. I thought that someone decided that since plugging devices into the FireWire or USB ports usually causes a notification to appear, they should be consistent and have a message appear for devices plugged. However, plugging and unplugging USB devices for which drivers are already installed doesn't cause a little notification window to appear; Vista simply plays a single pizzicato string note when you plug them in and two pizzicato string notes when you unplug them.
It may be some kind of security measure. Maybe it's meant to warn you in cases where the machine is out of line-of-sight of the keyboard, mouse and display (wireless keyboard and mouse, really long VGA cable?). In such a setup, you'd probably want to know if someone's jacked into your machine, trying to listen to or record whatever sounds or tunes are playing. It could be the basis for an RIAA-scripted horror movie: “Get out quickly! The pirate's in your house!”
Whatever the reason for this feature's inclusion, it makes it seems as if Vista's trying too hard to impress you.