  We examine the dispersive properties of linear fast standing modes in
transversely nonuniform solar coronal slabs with finite gas pressure, or,
equivalently, finite plasma beta. We derive a generic dispersion relation
governing fast waves in coronal slabs for which the continuous transverse
distributions of the physical parameters comprise a uniform core, a uniform
external medium, and a transition layer (TL) in between. The profiles in the TL
are allowed to be essentially arbitrary. Restricting ourselves to the first
several branches of fast modes, which are of most interest from the
observational standpoint, we find that a finite plasma beta plays an at most
marginal role in influencing the periods ($P$), damping times ($\tau$), and
critical longitudinal wavenumbers ($k_{\rm c}$), when both $P$ and $\tau$ are
measured in units of the transverse fast time. However, these parameters are in
general significantly affected by how the TL profiles are described. We
conclude that, for typical coronal structures, the dispersive properties of the
first several branches of fast standing modes can be evaluated with the much
simpler theory for cold slabs provided that the transverse profiles are
properly addressed and the transverse Alfv\'en time in cold MHD is replaced
with the transverse fast time.
