The 3rd prong earth ground is the most important. There is a workaround, get a two to three prong adaptor, it will have a metal clasp or sometimes a short green wire, make sure the one you get does, the clasp/wire is attached to the center screw of the wall outlet plate cover, now you are grounded properly.
Assuming the electrician did his job correctly when the outlet was installed.(rare) But you did the best you can do. Enjoy!