  We describe recent three-flavor QCD lattice data for the pressure, speed of
soun d and interaction measure at nonzero temperature and vanishing chemical
potentia l within a virial expansion. For the deconfined phase we use a
phenomenological model which includes non-pert urbative effects from dimension
two gluon condensates that reproduce the free en ergy of quenched QCD very
well. The hadronic phase is parameterized by a generalized resonance-gas model.
Furthermore, we extend this approach to finite quark densities introducing an
ex plicit $\mu$-dependence of the interaction. We calculate pressure,
quark-number density, entropy and energy density and compare to results of
lattice calculatio ns. We, additionally, investigate the structure of the phase
diagram by calculating the isobaric and isentropic lines as well as the
critical endpoint in the ($T, \mu_q $)-plane.
