Your DVD player will play them if you take it to the US but their supply voltage is generally 110v. Some electronic appliances have a small voltage selector switch on the back where you can set them for 100v or 230v. If it doesn't have this option then you'd need to run it in the US using a 110v-230v step up transformer.
If you're going to buy a multi region DVD then wait till you get there before you purchase it, that way you'll get one that works on the correct voltage.
If you've got any comments on the DVD region code and how such copyright measures help get the artists paid please feel free to
join the debate in this thread.