Will anti-virus on a host computer protect the entire network?

Scott P asked: On a home network, will the anti-virus that is installed on the host computer protect other computers on the same network?

How do i password protect an external hard drive i am sharing on a home network?

jozue06 asked: i have an external HD hooked up to one of my computers on my wireless home network. i want to share in on the network, but have it password protected. how do i do this?