One of the greatest things you’ll find on Windows Vista is it’s answer to the iCal, Windows Calendar. Unlike many other desktop calendars, Windows Calendar allows you to subscribe to various types of calendars such as Google Calendar and receive updates. This is great if you prefer Windows Calendar over other calendars but still want to receive data from online sources. For example, Gmail allows you to quickly add an event notice from your email to Google Calendar, but not Windows Calendar.
First you need to get to the iCal link of your calendar, since Windows Calendar can only subscribe to the .ics format. To do so, navigate to Settings > Calendars > Name of your Calendar
Scroll down and you will see a shiny ICAL button. Right click it, and choose Copy Shortcut or Copy Link Location.
Then head over to Windows Calendar and click on Subscribe at the top. You’ll be taken to this screen where you can paste the URL of your calendar into the textbox.