  We consider the prospects for detecting effects due to the Higgs exchange
diagram in high energy mu^+ mu^-$, e^+ e^-, and tau^+ tau^- collisions
producing a pair of W bosons. The processes l^+l^- -> W^+W^- (with l=mu,e,tau)
are analyzed, analytically and via numerical simulations, to determine the
center of mass energy, sqrt{s}_H, where the effects from Higgs exchange become
relevant. The scaling of sqrt{s}_H with the mass of the incoming leptons is
also studied. Special consideration is given to the W^+W^- -> l^pm} nu_l jj
final state after experimental acceptance cuts are imposed. Angular cuts are
shown to be able to significantly lower sqrt{s}_H.
