Sidebar allows you to access mini-applications called Gadgets. Sidebar is similar to Konfabulator or Macintosh OS X's Dashboard, which call their mini-applications Widgets.
Speech Recognition lets users control their computers and create documents using their voices. Vista has a speech-activated user interface as well as a general voice dictation application.
Windows Mail replaces Outlook Express for home users and includes anti-phishing tools.
Windows Calendar, also for home users, is an interactive calendar application. In addition to allowing users to keep track of appointments, it can be used to send e-mail invitations to events.
SuperFetch pre-loads frequently-used applications into the memory so they can start up faster.
ReadyBoost lets people add RAM to their system with a USB thumb drive.
Sleep lets you quickly resume working by storing files that are currently in use. On desktop computers, these files are saved in the computer's RAM and on the hard drive. On laptop computers, the files are saved to the hard drive only when the battery power wanes.
clipped from: computer.howstuffworks.com