I will discuss recent efforts to carry out well resolved (kpc) adaptive mesh refinement cosmological simulations of galaxy formation. In particular I will show that, provided the cosmological parameters are set to their current preferred values (WMAP5) and that internal extinction is properly taken in to account, these simulations show reasonable agreement with ultra deep determination of the luminosity function of galaxies at z > 4. In an effort to tease out the impact of cold gas accretion, star formation and feedback on galaxy formation and evolution I will then present ultra-high resolution (sub pc) re-simulations of a Milky Way like galaxy at high redshift. More specifically, I will focus on the ability of such simulations to generate powerful galactic winds and the consequences of this feedback for the star formation history of the modeled galaxy.