Can you change web browsers in messenger ?

Is it possible to change the browser that Windows Messenger 4.7.2009 uses,
when you click to read hotmail account e-mail. Since upgrading to 4.7.2009
for the supposid security fixes, no matter which application I set to be my
default web browser, Internet Explorer opens up.
Also, due to having installed MSN messenger 5.x, when IE opens up to read
my hotmail account, MSN messenger is started up as well. I prefer to use
Windows Messenger 4.7.x and would appreciate any information or
instructions.
Thanks,
JasonT