Anti Spam Hardware Hardware Firewall, Software Firewall, Anti-Virus, Anti-Spam - Is It Enough?

Hardware Firewall, Software Firewall, Anti-Virus, Anti-Spam - is it enough? - anti spam hardware

I have a Linksys firewall terminates the connection cable.
The wireless function of the firewall is turned off, because I have a 100 MB Ethernet cable throughout the house.

There are four computers in the house. Each run Adaware, AVG Anti-Virus and Kerio Personal Firewall.

Can you join the network and get privelidges executive, while my PC? How can we better protect against?

My NAS 250 GB Buffalo Technology LinkStation. It runs on Linux, but has a user interface, the ability to offer little or no change security settings. What is fever?

I think I've covered the basics, but I'm still about compromising the security of HTTP traffic concerns - I would not worry about it and what can I do?