quistion about wifi vs 3g for surfing web


Android Enthusiast
So I leave my wifi off when not using it, was wondering lets say I want to surf the net in my house on the wifi, I turn it on and start surfing, is the Eris droid smart enough to use the wifi over the 3g when the wifi is on?
just wondering because I know the wifi use way less battery juice surfing than the 3g/cell towers.