Ok, here's an outside the 'box' alternative- how to remove paint from
outlet covers/faceplates. Get them wet, scrub with copper wool- I've
done it. So no need to replace anything. Really, though, you want to
have properly grounded circuits. It's safer. You've gotten some good
suggestions- but why not just call an electrician, get a free
estimate. Sometimes your local hardware store will give you a few
names of local, reliable people if you don't know any. This way,
you'll have the situation looked at, get cost estimates,
recommendations re minimal/ ideal upgrades etc. You'll actually have
an experienced person familiar with local construction look at your
wires, as none of us can do. Then you make your decision.