X-ray reflectivity has been used for investigations of molecular ordering in thin liquid films of polydimethylsiloxanes (PDMS) of low molecular weights deposited on a Relished silicon wafer. The liquid films we studied were similar to 40-90 Angstrom thick. Evidence of molecular layering induced by geometrical confinement by a hard wall is obtained for thin films of lowest molecular weight PDMS. The positions of the secondary maxima in the Patterson functions, P(z), for these samples reveal a periodicity of about 10 Angstrom, consistent with the size of PDMS molecules. Further increasing the molecular weight leads to suppression of P(z) oscillations, causing the electron density profile to become more uniform. For higher molecular weight PDMS, a flatlike conformation of molecules absorbed on a solid surface is observed.