  M dwarfs have been found to often have super-Earth planets with short orbital
periods. Such stars are thus preferential targets in searches for rocky or
ocean planets in the solar neighbourhood. In a recent paper (Bonfils et al.
2011), we announced the discovery of respectively 1 and 2 low mass planets
around the M1.5V stars Gl433 and Gl667C. We found those planets with the HARPS
spectrograph on the ESO~3.6-m telescope at La Silla Observatory, from
observations obtained during the Guaranteed Time Observing program of that
instrument. We have obtained additional HARPS observations of those two stars,
for a total of respectively 67 and 179 Radial Velocity measurements for Gl433
and Gl667C, and present here an orbital analysis of those extended data sets
and our main conclusion about both planetary systems. One of the three planets,
Gl667Cc, has a mass of only M2.sin(i)~4.25 M_earth and orbits in the central
habitable zone of its host star. It receives just 10% less stellar energy from
Gl667C than the Earth receives from the Sun. However planet evolution in
habitable zone can be very different if the host star is a M dwarf or a
solar-like star, without necessarily questioning the presence of water. The two
other planets, Gl433b and Gl667Cb, both have M2.sin(i) of ~5.5 M_earth and
periods of ~7 days. The Radial Velocity measurements of both stars contain
longer time scale signals, which we fit as longer period Keplerians. For Gl433
that signal probably originates in a Magnetic Cycle, while a longer time span
will be needed to conclude for Gl667C. The metallicity of Gl433 is close to
solar, while Gl667C is metal poor with [Fe/H] ~ -0.6. This reinforces the
recent conclusion that the occurence of Super-Earth planets does not strongly
correlate with stellar metallicity.
