Because of my recent adventures with Windows Vista on my Lifebook, I've had to learn about and deal with the differences between Vista and XP in third-party device driver distribution and updates. Windows XP is very "laissez-faire" about such updates; I have occasionally seen one show up in Windows Update for XP under "Optional Updates", but I don't recall ever having seen one as a mandatory or automatic update. Vista, on the other hand, is very aggressive about distributing such updates. I have seen a number of them included in the mandatory/automatic section of Windows Update for Vista. This difference in approach extends even to locating drivers for newly installed devices. Windows XP will always ask when a new device is connected whether you want to search on the internet for the latest driver - and even when you say "yes", it seems to me that it most often fails to find anything. Vista, however, will always search the internet for drivers, and seems to find what it needs the majority of the time. In fact, some device manufacturers appear to be taking advantage of this fact - the last time I went to download the driver for a Philips webcam, I found a note on the Philips web page saying that for Vista systems it was not necessary to download the driver because the latest version would be found automatically by Windows Update.
While this does relieve the user of having to check for updates from time to time, it is not a universally good thing. There are situations where someone might not need or even want to install an updated driver. The Logitech QuickCam software comes to mind; there have been numerous cases of compatibility problems with specific versions of Logitech camera drivers or QuickCam softare, and once you find a version which works properly, you probably wouldn't want Vista to turn around and install a "newer" version on top of it. Similar situations have been known with display drivers and audio drivers from various suppliers.
Even the automatic download and installation of the latest drivers when new hardware is connected can cause a problem. Once again webcams are a good example of this. Many webcams today are compatible with the generic Microsoft USB Video Device (UVC) driver; with Windows XP, the simplest way to get that driver installed was to just connect the device without pre-loading the camera suppliers' device drivers. When XP was unable to find drivers specific to the camera, and it saw that the camera was UVC compatible, it would load the UVC drivers for it. Try the same thing with Vista, however, and it will download and install the latest device-specific drivers from the internet.
This is only the tip of the iceberg. I'll be writing a lot more in the next few days about responsibilities and conflicts over driver and software updates.