I was able to set Live Hotmail as Default this way...

It has taken me all afternoon to come up with a method to set my default
email to my Live Hotmail account.

First, Download, Extract, and Run the program at this site
http://www.winhelponline.com/article...ows-Vista.html
--> Set Windows Live Hotmail as the Default program.

Second, go to Run and enter regedt32. There, go to
HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows Live/Communications
Clients/Shared --> Right click on Mail Install Root; Select Modify; Change
C:\Program Files\Windows Live\Mail\ to C:\Program Files\Windows Live\Hotmail\
--> Then click on File\Exit

Third, reboot your machine.

Now the MailTo: and Mail defaults should be set to go to your Windows Live
Hotmail login, or directly to the mail client if you have it save your
username and password.