Abstract: We perform a Gutzwiller projected wavefunction study for the spin-1/2 Heisenberg model on the Kagome lattice to compare energies of several spin-liquid states. The result indicates that a U(1)-Dirac spin-liquid state has the lowest energy. Furthermore, even without variational parameters, the energy turns out to be very close to that found by exact diagonalization. We show that such a U(1)-Dirac state can be a stable quantum phase whose low energy physics is governed by four flavors of two-component Dirac fermions coupled to a U(1) gauge field. These results are discussed in the context of recent experiments on ZnCu3(OH)6Cl2.