  We calculate within the Boltzmann equation approach the charged impurity
scattering limited low temperature electronic resistivity of low density
$n$-type inversion layers in Si MOSFET structures. We find a rather sharp
quantum to classical crossover in the transport behavior in the $0 - 5$K
temperature range, with the low density, low temperature mobility showing a
strikingly strong non-monotonic temperature dependence, which may qualitatively
explain the recently observed anomalously strong temperature dependent
resistivity in low-density, high-mobility MOSFETs.
