  We introduce a new set of simulations of Milky Way-sized galaxies using the
AMR code ART + hydrodynamics in a $\Lambda$CDM cosmogony. The simulation series
is named GARROTXA and follow the formation of a halo/galaxy from z~$=$~60 to
z~$=$~0. The final virial mass of the system is
$\sim$7.4$\times$10$^{11}$M$_{\odot}$. Our results are as follows: (a) contrary
to many previous studies, the circular velocity curve shows no central peak and
overall agrees with recent MW observations. (b) Other quantities, such as
M$\_{*}$(6$\times$10$^{10}$M$_\odot$) and R$_d$ (2.56 kpc), fall well inside
the observational MW range. (c) We measure the disk-to-total ratio
kinematically and find that D/T=0.42. (d) The cold gas fraction and star
formation rate (SFR) at z=0, on the other hand, fall short from the values
estimated for the Milky Way. As a first scientific exploitation of the
simulation series, we study the spatial distribution of the hot X-ray luminous
gas. We have found that most of this X-ray emitting gas is in a halo-like
distribution accounting for an important fraction but not all of the missing
baryons. An important amount of hot gas is also present in filaments. In all
our models there is not a massive disk-like hot gas distribution dominating the
column density. Our analysis of hot gas mock observations reveals that the
homogeneity assumption leads to an overestimation of the total mass by factors
3 to 5 or to an underestimation by factors $0.7-0.1$, depending on the used
observational method. Finally, we confirm a clear correlation between the total
hot gas mass and the dark matter halo mass of galactic systems.
