If the old outlets are grounded, you can replace them with new
grounded outlets. HOWEVER, you are supposed to bring the box up to
code. That means the ground wire attaches to the BOX and the green
screw on the outlet. If the box is grounded using the conduit, you
have to install a green screw or clip and run the wire from the box to
the outlet.

This isn't hard to do and really improves your safety factor.