A supersymmetric model with four generations is proposed, in which the
top quark is approximately degenerate in mass with the W-+/- gauge bo
son, m(t) similar or equal to m(W), leading to values of R(b) in bette
r agreement with the present experimental data than in the Standard Mo
del. The model shares many of the good features of the minimal supersy
mmetric extension of the Standard Model (MSSM), such as the unificatio
n of gauge and Yukawa couplings at a common high energy scale. The mod
el differs from the MSSM by re-interpreting the Tevatron ''top-quark''
events as the production of the fourth generation quark t', which dec
ays dominantly to bW(+). The top quark decays primarily into supersymm
etric particles, t --> (t) over tilde<(chi)over tilde (0)(1)>, with (t
) over tilde --> <c(chi)over tilde (0)(1)>, thereby evading previous s
earches. Light supersymmetric particles are predicted to lie in the ma
ss range between 25 and 70 GeV, which together with the fourth generat
ion leptons provide a rich spectrum of new physics which can be probed
at LEP-2 and the Tevatron.