i use World construction set with scene express, imports and exports fine with Lightwave 5.1.
i dont use a pc so i dont know about 7.5.
anyway WCS support ppc and the results are infact AMAZING!, i have seen bryce in action (PC) it was ok but the gui was pretty annoying and quirky to use.
that said , fo easy landscapes (non animated water etc/reflections bla bla) then i use SCENERY ANIMATOR , decent stuff and support lw5.x objects fine and other way around.
cheers