  We present new or improved methods for calculating NLTE, line-blanketed model
atmospheres for hot stars with winds (spectral types A to O), with particular
emphasis on a fast performance. These methods have been implemented into a
previous, more simple version of the model atmosphere code FASTWIND
(Santolaya-Rey et al.1997) and allow to spectroscopically analyze rather large
samples of massive stars in a reasonable time-scale, using state-of-the-art
physics.
  We describe our (partly approximate) approach to solve the equations of
statistical equilibrium for those elements which are primarily responsible for
line-blocking and blanketing, as well as an approximate treatment of the
line-blocking itself, which is based on a simple statistical approach using
suitable means for line opacities and emissivities. Furthermore, we comment on
our implementation of a consistent temperature structure.
  In the second part, we concentrate on a detailed comparison with results from
those two codes which have been used in alternative spectroscopical
investigations, namely CMFGEN (Hillier & Miller 1998) and WM-Basic (Pauldrach
et al. 2001). All three codes predict almost identical temperature structures
and fluxes for lambda > 400 A, whereas at lower wavelengths a number of
discrepancies are found. Optical H/He lines as synthesized by FASTWIND are
compared with results from CMFGEN, obtaining a remarkable coincidence, except
for the HeI singlets in the temperature range between 36,000 to 41,000 K for
dwarfs and between 31,000 to 35,000 K for supergiants, where CMFGEN predicts
much weaker lines. Consequences due to these discrepancies are discussed.
