  We define deformations of W-algebras associated to complex semi-simple Lie
algebras by means of quantum Drinfeld-Sokolov reduction procedure for affine
quantum groups. We also introduce Wakimoto modules for arbitrary affine quantum
groups and construct free field resolutions and screening operators for the
deformed W-algebras. We compare our results with earlier definitions of
q-W-algebras and of the deformed screening operators due to Awata, Kubo, Odake,
Shiraishi (q-alg/9507034, q-alg/9508011, q-alg/9612001), Feigin, E. Frenkel
(q-alg/9508009) and E. Frenkel, Reshetikhin (q-alg/9708006). The screening
operator and the free field resolution for the deformed W-algebra associated to
the simple Lie algebra sl(2) coincide with those for the deformed Virasoro
algebra introduced in q-alg/9507034.
