From the Cable Modem to SR-200's WAN port, connect both with a Ethernet cable.
SR-200 Router only have ethernet port and it has no USB port.
You can't have both ethernet cable and USB cable connected to the cable modem at the same time. If you are to use the SR-200 then remove the USB Cable.
So
From SR-200
Port 1 connect ethernet cable to CPU
Port 2 connect ethernet cable to VP-100/200
Port 3 - empty can be used to connect to other CPU (ethernet)
Port 4 - empty can be used to connect to other CPU (ethernet)
If you are to use USB cable then you can't use SR-200 so that means you connect USB cable from Cable Modem to CPU.
VP-100/200 must be set to the DMZ address (192 . 168 . 0 . 125) while other CPU are set to DHCP