We investigate whether the LMC Cepheid PL relation given by OGLE III Cepheids is linear or nonlinear at VI wave-bands. We cross-correlate the OGLE III Cepheids with the 2MASS survey to produce JHK LMC PL relations. We find that the VIJH band PL relations are linear whilst the WK relations are marginally nonlinear. We present very preliminary results on the estimation of Hubble's constant via a calibration of the SNIa Hubble diagram using a linear and non-linear PL relation in the LMC obtained from OGLE III data. We find our estimates vary from those derived using OGLE II data and moreover there is a roughly 5% difference in the estimated value of H0 depending on whether a linear or non-linear PL relation is assumed. We discuss possible reasons for this result.