  Using an analytic model calibrated against numerical simulations, we
calculate the central densities of dark matter halos in a ``conventional'' cold
dark matter model with a cosmological constant (LCDM) and in a ``tilted'' model
(TLCDM) with slightly modified parameters motivated by recent analyses of
Ly-alpha forest data. We also calculate how warm dark matter (WDM) would modify
these predicted densities by delaying halo formation and imposing phase space
constraints. As a measure of central density, we adopt the quantity D_{V/2},
the density within the radius R_{V/2} at which the halo rotation curve falls to
half of its maximum value, in units of the critical density. We compare the
theoretical predictions to values of D_{V/2} estimated from the rotation curves
of dark matter dominated disk galaxies. Assuming that dark halos are described
by NFW profiles, our results suggest that the conventional LCDM model predicts
excessively high dark matter densities, unless there is some selection bias in
the data toward the low-concentration tail of the halo distribution. A WDM
model with particle mass 0.5-1 keV provides a better match to the observational
data. However, the modified cold dark matter model, TLCDM, fits the data
equally well, suggesting that the solution to the ``halo cores'' problem might
lie in moderate changes to cosmological parameters rather than radical changes
to the properties of dark matter. If CDM halos have the steeper density
profiles found by Moore et al., then neither conventional LCDM nor TLCDM can
reproduce the observed central densities.
