Hi thanks for this reply, sorry for the delay, it's been busy here.
I probably didn't describe my network correctly so here goes.
Cable Modem (Virgin) don't know the model.
This is connected to:
Router - Netgear RP614 (the box says it has an SPI Firewall and a NAT firewall. I've not configured it at all.
The Buffalo drive is connected to this router.
This is connected to another two switches,
My concern is that the firewall on the router is not going to be sufficient since it's at the default settings. Parhaps I'm being too cautious here and imagine that we get probed by persistent hackers and that these hardware firewalls are not much use unless you set them up properly.