We present the current status of our ongoing calculations of pseudoscalar
meson decay constants for mesons that contain one light and one heavy quark
(f_B, f_{B_s}, f_D, f_{D_s}). We are currently generating new gauge
configurations that include dynamical quarks and calculating the decay
constants. In addition, we have several new results for the static
approximation. Those results, as well as several refinements to the analysis,
are new since Lattice '96. Our current (still preliminary) value for f_B is 156
+- 11 +- 30 +- 14 MeV, where the first error is from statistical and fitting
errors, the second error is an estimate of other systematic errors within the
quenched approximation and the third error is an estimate of the quenching
error. For the ratio f_{B_s}/f_B, we get 1.11 +- 0.02 +- 0.03 +- 0.07.Comment: 8 pages, 9 figures, LaTeX, uses espcrs2, epsf, Invited talk presented
by S. Gottlieb at Lattice QCD on Parallel Computers, University of Tsukuba,
March, 1997, to appear in the proceeding
