  MILC collaboration results for \fB, \fBs, \fD, \fDs and their ratios are
presented. These results are still preliminary, but the analysis is close to
being completed. Sources of systematic error, both within the quenched
approximation and from quenching itself, are estimated. We find, for example,
$f_B=153\pm 10 {}^{+36}_{-13} {}^{+13}_{-0} MeV$, and $f_{B_s}/f_B = 1.10 \pm
0.02 {}^{+0.05}_{-0.03} {}^{+0.03}_{-0.02}$, where the errors are statistical,
systematic (within the quenched approximation), and systematic (of quenching),
respectively. The extrapolation to the continuum and the chiral extrapolation
are the largest sources of error. Present central values are based on linear
chiral extrapolations; a shift to quadratic extrapolations would raise $f_B$ by
$\approx20$ MeV and make the error within the quenched approximation more
symmetric.
