Look at our system:
Mercury: Ball of rock, no atmosphere, high solar radiaton, no known water. DEAD
Venus: Ball of rock, thick CO2/sulfuric acid atmosphere, high temperatures, high pressures, no known water. DEAD
Mars: Ball of rock, thin CO2 atmosphere, low temperatures, high radiation, but known water ice. Possible life-supporter
Jupiter: Ball of Gas. DEAD
Saturn: Ball of Gas. DEAD
Uranus: Ball of gas. DEAD
Neptune: Ball of gas. DEAD
Earth: Ball of rock, thick atmosphere, magnetic field, liquid water, active tectonic cycle, etc. Life supporting
1/8th of all the planets in this system can support life. We've only "seen" a few planets in ideal conditions, and many of them are simply detected through doppler shifts from their parent star. Life-supporting planets or moons are out there. We just need to find them.
:2cents: