Yes. If bother are 100mbps Ethernet they are compatible.
I assume you mean a Motorola router and a Net gear Hub.
Are you sure the Motorola is a router? Do you have the model number.
My guess is you have a Motorola modem that behaves as residential gateway.
If it is the one I am thinking about, you will need to replace it someday.
You might consider getting a new Como modem.router/wireless in on unit.
But yes, there should not be a problem using a hub after the modem.
OOPS. You have to make sure that modem does act like a router. Otherwise you can NOT use just a hub after it. I tried that on a Motorola modem and it don't work. You use a hub only after a router. Same for a switch. With current prices, you might as well buy a router.
Thee are other possibilities, but what I has said here is what you need to know for a typical residential gateway.