Here are the instructions on setting up your Hotmail (Windows Live Mail) email as a default email client so that it can pick it up when you click on an email address in the business card section within a contact:
How do I make my mail client as default?
1. Click Start Menu and select Default Programs.
2. Select the first label, Set your default programs link label.
3. The you will see a list of icons and program names, select one for windows live mail and click Set this program as default command link.
This will now set up the windows live mail as the default so that when you go into your account and click on an email address it will pull up your windows live email.
If for some reason after following the above instructions you are unable to set-up Hotmail or Windows Live Mail as your default email client please contact the Hotmail helpline on: 0843 506 9260