  We model the combined effects of photoionization and momentum--driven winds
from O--stars on molecular clouds spanning a parameter space of initial
conditions. The dynamical effects of the winds are very modest. However, in the
lower--mass clouds, they influence the morphologies of the HII regions by
creating 10pc--scale central cavities.\\ The inhomogeneous structures of the
model GMCs make them highly permeable to photons, ionized gas and supernova
ejecta, and the leaking of ionized gas in particular strongly affects their
evolution, reducing the effectiveness of feedback. Nevertheless, feedback is
able to expel large fractions of the mass of the lower escape--velocity clouds.
Its impact on star formation is more modest, decreasing final star formation
efficiencies by 10--20$\%$, and the rate of change of the star formation
efficiency per freefall time by about one third. However, the clouds still form
stars substantially faster than observed GMCs.
