We report on combined transport and magnetic decoration studies of pin
ned and moving vortex structures in the low-field (<100 Oe) regime. Th
ermal and current annealing processes show that the pinned equilibrium
state of the vortex array has fewer topological defects than that obs
erved when the structure first starts to become unpinned, and more def
ects than observed at high vortex velocities. This is in agreement wit
h recent experiments and theoretical results.