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.