Windows Firewall is required, if network-shared printers are to be used, in Server 2008 R2 and Windows 7. See here:
http://support.microsoft.com/kb/2123653
But there are still many instances where Windows Firewall gets in the way. In these cases, set up a Group Policy for Windows Firewall with Advanced Security:
Computer Configuration,
Policies,
Windows Settings,
Security Settings,
Windows Firewall with Advanced Security,
Windows Firewall with Advanced Security – LDAP://cn={GUID},cn=….
and Allow all connections both inbound and outbound. That way the APIs all run, but no interferences.