  We present a detailed analysis of the dynamical properties of a simulated
disk galaxy assembled hierarchically in the Lambda CDM cosmogony. At z=0, two
distinct dynamical components are identified on the basis of the orbital
parameters of stars in the galaxy: a slowly rotating, centrally concentrated
spheroid and a disk-like component largely supported by rotation. These
components are also recognized in the surface brightness profile of the galaxy,
which can be very well approximated by the superposition of an R^{1/4} spheroid
and an exponential disk. However, neither does the dynamically-identified
spheroid follow de Vaucouleurs' law nor is the disk purely exponential, a
resultwhich calls for caution when estimating the importance of the disk from
traditional photometric decomposition techniques. The disk may be further
decomposed into a thin, dynamically cold component with stars on nearly
circularorbits and a hotter, thicker component with orbital parameters
transitional between the thin disk and the spheroid. The spheroid is old, and
has essentiallyno stars younger than the time elapsed since the last major
accretion event ~8 Gyr ago. The majority of thin disk stars, form after the
merging activity is over, although a significant fraction ~15% of thin-disk
stars are old enough to predate the last major merger event. This unexpected
population of old disk stars consists mainly of the tidal debris of satellites
whose orbital plane was coincident with the disk and whose orbits were
circularized by dynamical friction prior to full disruption. Our results
highlight the role of satellite accretion events in shaping the disk and the
spheroidal component and reveal some of the clues to the assembly process of a
galaxy preserved in the detailed dynamics of old stellar populations.
