You are using #2 gauge wire so I am assuming you are going to use a double pole, 100-amp breaker to feed the sub panel on your house.
You will need to run three #2 gauge wires,(two hots and one neutral), from your main panel at the garage to the sub panel on your house. Along with one #8 gauge copper wire for your equipment ground, (Earth).
This is all of the grounding or Earthing that you will need to do. You don't need to drive ground rods in the earth. The #8 gauge equipment ground comming from the garage is sufficient for your ground faults. You still need to run a separate bare copper ground wire from the sub panel to your gas line and metal water line.
Like Tom posted, you will need to keep your equipment ground and neutral wire separate inside of the sub panel on your house. To do this you will need a ground buss bar bolted directly to the sheet metal of the can. (for all of your grounds,(earths), to land on. (Usually the bare copper wires). Then another buss bar called the neutral buss bar mounted inside of the sub panel on your house. Mount it in such a way that it is insulated from the metal can. They come with a plastic spacer to keep it off of the metal can. This is were the #2 neutral wire will land, comming from the main panel at the garage. Also this is were all of the white wires that go into your house will land.
The sub panel will need a 100-amp main breaker. Make sure you don't get a Main-Lug-Only type sub panel. (MLO).
Tev
