  Recent results have shown that many of the known extrasolar planetary systems
contain regions which are stable for both Earth-mass and Saturn-mass planets.
Here we simulate the formation of terrestrial planets in four planetary systems
-- 55 Cancri, HD 38529, HD 37124, and HD 74156 -- under the assumption that
these systems of giant planets are complete and that their orbits are
well-determined. Assuming the giant planets formed and migrated quickly, then
terrestrial planets may form from a second generation of planetesimals. In each
case, Moon- to Mars-sized planetary embryos are placed in between the giant
planets and evolved for 100 Myr. We find that planets form relatively easily in
55 Cnc, with masses up to 0.6 Earth masses and in some cases substantial water
contents and orbits in the habitable zone. HD 38529 is likely to support an
asteroid belt but no terrestrial planets of significant mass. No terrestrial
planets form in HD 37124 and HD 74156, although in some cases 1-2 lone embryos
survive for 100 Myr. If migration occurred later, depleting the planetesimal
disk, then massive terrestrial planets are unlikely to form in any of these
systems.
