The next generation of Windows Live Calendar is now available. I much prefer keeping things like my calendar and email online rather than stored on my hard drive; I am protected against losing my files in the case of a hard drive failure, or having to reinstall windows, etc. Plus, I can access my mail and calendar from work, or anywhere with an Internet connection.
You can share your calendar with your friends, synch it with Outlook (using Outlook Connector, a separate download), use birthday and holiday calendars and more.
Have a look here for more information: