  Numerical models of disc galaxy formation predict the existence of extended,
hot ( T~10^6 K) gas haloes around present day spirals. The X-ray luminosity of
these haloes is predicted to increase strongly with galaxy mass. However,
searches for their X-ray emission have not been successful so far. We calculate
the all sky O VII column density distributions for the haloes of three Milky
Way like disc galaxies, resulting from cosmological high-resolution,
N-body/gasdynamical simulations. We perform calculations both including the
disc gas and without it, so the disc contribution to the column density is
quantified. It is found that the column densities estimated for Milky Way-like
galaxies are just below the observational upper limit, making a test of the hot
halo paradigm likely within observational reach.
