cable modem connections

I'm currently running two PCs on my cable modem.
I'm using a D-Link router and CAT5E to connect them.
My modem has the ability to connect one PC via USB and a second PC
with ethernet cable (eliminating the need for the router)

Is there any advantage to hooking up one PC using the USB?
Also, as far as security, I've heard that a router besides having it's own
built in firewall feature masks your real ISP, true or false?
Would I be giving up a modecum of secuity by eliminating the router
and gaining nothing as far as connection speed?

Any advise on this would be greatly appreciated.

 

I believe it is an either/or situation - either USB or Ethernet not both.. "verified" A USB connection can be used if your computer has an available USB port. Although no card installations are necessary with USB, the installation of a USB driver is required. (See page for the your specific type of modem.) The USB interface does not allow for more than one computer to be connected to the cable modem. & "it is possible that the addition of other devices to the USB port could degrade the performance of the cable modem. This is because other devices can use up bandwidth that the cable modem would otherwise be using.

As far as masking you IP - most ISP's do that via NAT More NAT it was to stretch the number of public IP addresses available for everyone.