  We examine the constraints that can be obtained on standard cold dark matter
models from the most currently used data set: CMB anisotropies, type Ia
supernovae and the SDSS luminous red galaxies. We also examine how these
constraints are widened when the equation of state parameter $w$ and the
curvature parameter $\Omega_k$ are left as free parameters. For the
$\Lambda$CDM model, our 'vanilla' model, cosmological parameters are tightly
constrained and consistent with current estimates from various methods. When
the dark energy parameter $w$ is free we find that the constraints remain
mostly unchanged, i.e. changes are smaller than the 1 sigma uncertainties.
Similarly, relaxing the assumption of a flat universe leads to nearly identical
constraints on the dark energy density parameter of the universe
$\Omega_\Lambda $, baryon density of the universe $\Omega_b $, the optical
depth $\tau$, the index of the power spectrum of primordial fluctuations $n_S$,
with most one sigma uncertainties better than 5%. More significant changes
appear on other parameters: while preferred values are almost unchanged,
uncertainties for the physical dark matter density $\Omega_ch^2$, Hubble
constant $H_0$ and $\sigma_8$ are typically twice as large. We found that
different methodological approaches on large scale structure estimates lead to
appreciable differences in preferred values and uncertainty widths. We also
found that possible evolution in SNIa intrinsic luminosity does not alter these
constraints by much, except for $w$, for which the uncertainty is twice as
large. At the same time, this possible evolution is severely constrained. We
conclude that systematic uncertainties for some estimated quantities are
similar or larger than statistical ones.
