When you say you cannot access Microsoft.com...can you please list the FULL address that you are trying to access?
If it is updates you must use Internet Explorer in order to do this, you cannot update using Firefox.
Please list the full address, as it would appear in your address bar on the browser so I can see if that could be the problem.
You say you installed Zone Alarm, what firewall were you using prior to that?
What are the security settings on your browsers?