I notice nobody's answered you on what looks like a simple enquiry. I have been having a look at the BT shop site, I think this maybe the router you're looking at: click here
It does say in the blurb;
4 Ethernet ports to enable wired connections to PC's, games consoles and other Ethernet-enabled equipment
The cable is supplied to allow devices that are not capable of using the wireless network to be connected using the Ethernet cable. I can't see any reason why you shouldn't use the cable to connect the static computer if that's your want.
That's my take on it anyway.