Among the many hidden new features of vista which belong to the category of "why didn't they do this in the first place", there is the new and improved support for displays and external displays in particular for a laptop.
In Windows XP, when you were attaching a display to your laptop, the resolution (and color depth) used was attached to the physical port, not to the display itself. So if you were moving around a lot with your laptop attaching many displays with many different resolutions, you had to reconfigure each time.
Vista's way is a bit different since the resolution and color depth are now attached to each specific display, and are automatically recalled upon connecting the cable. Now, when you attach a display, you can hear the "device connected" sound, the same used when connecting an USB device or PCMCIA card.
This also goes along with the presentation mode which allows to hide your trolling background when hosting a presentation. This is particularly useful at Epitech :)