  We present updated standard solar models (SSMs) that incorporate the latest
results for nuclear fusion rates, recently published. We show helioseismic
results for high and low metallicity compositions and also for an alternative
set of solar abundance, derived from 3D model atmospheres, which give
intermediate results. For the high and low metallicity models, we show that
current solar neutrino data can not differentiate between models and that a
measurement of the CNO fluxes is necessary to achieve that goal. A few
additional implications of a hypothetical measurement of CNO neutrinos, both in
terms of solar and stellar physics, are discussed.
