Microsoft propose an add-in for Outlook to help you planning travel.
This add-in includes search for plane, hotel or car based on Bing Travel service.
The search is done directly from Outlook and will provide you the best travel plan based on a high volume of data (airfare, hotel rate…)
You can download it from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=64ca7137-d8d8-49f1-ae42-00e9fcbf775f.
Once installed, the add-in is available from the add-in menu
A new window will pop up to ask you your trip