Firewall security of Windows guest under KVM/Qemu

[paradigm-X]

I am scratching my head trying to figure out whether there is any point in having a Windows guest install a firewall when it is connected to the KVM/Qemu host network with NAT on a home LAN, given that the host, and network router itself, already has a firewall set up? If not, then why incur the overhead? Seems like using an AV on it would be sufficient. Any thoughts on this point would be welcome, and I am not interested in soliciting a protracted argument by any means.

[eccerr0r]

Treat the VM the same way as you would do a physical box. That's about all you have to do with it.
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Intel Core i7 2700K@ 4.1GHz/HD3000 graphics/8GB DDR3/180GB SSD
What am I supposed watching?