  We first discuss why the uncomfortable fine-tuning of the parameters of the
Lambda-CDM cosmological model provides continuing, strong motivation to
investigate Hubble's Constant. Then we review evidence from the HST Key Project
that there is a significant scale error between raw Cepheid and Tully-Fisher
distances. An analysis of mainly HST Distance Scale Key Project data shows a
correlation between host galaxy metallicity and the rms scatter around the
Cepheid P-L relation, which may support a recent suggestion that the P-L
metallicity dependence is stronger than expected. If Cepheids do have a
significant metallicity dependence then the Tully-Fisher scale error increases
and the distances of the Virgo and Fornax clusters extend to more than 20Mpc,
decreasing the value of Ho. Finally, if the Cepheids have a metallicity
dependence then so do Type Ia Supernovae since the metallicity corrected
Cepheid distances to eight galaxies with SNIa would then suggest that the SNIa
peak luminosity is fainter in metal poor galaxies, with important implications
for SNIa estimates of qo as well as Ho.
