  The colliding wind binary (CWB) systems \eta\ Carinae and WR140 provide
unique laboratories for X-ray astrophysics. Their wind-wind collisions produce
hard X-rays that have been monitored extensively by several X-ray telescopes,
including RXTE. To interpret these RXTE X-ray light curves, we model the
wind-wind collision using 3D smoothed particle hydrodynamics (SPH) simulations.
Adiabatic simulations that account for the absorption of X-rays from an assumed
point source at the apex of the wind-collision shock cone by the distorted
winds can closely match the observed 2-10keV RXTE light curves of both \eta\
Car and WR140. This point-source model can also explain the early recovery of
\eta\ Car's X-ray light curve from the 2009.0 minimum by a factor of 2-4
reduction in the mass loss rate of \eta\ Car. Our more recent models relax the
point-source approximation and account for the spatially extended emission
along the wind-wind interaction shock front. For WR140, the computed X-ray
light curve again matches the RXTE observations quite well. But for \eta\ Car,
a hot, post-periastron bubble leads to an emission level that does not match
the extended X-ray minimum observed by RXTE. Initial results from incorporating
radiative cooling and radiatively-driven wind acceleration via a new
anti-gravity approach into the SPH code are also discussed.
