The level of Firewall/anti-virus protection is directly related to the type of sites to which you expose your system. If you consistently go to dangerous sites, you may want to use something a little more specific to the type of infections that might be encountered.
I would say for most folks, the Microsoft stuff is enough if you allow MSE to do periodic scans. There could still be situations arising that might need additional help. If I do encounter additional problems and my basic protection cannot handle it, there are other utilities that can be brought to bear to help.