So, what's the advantage?

Speed is one big plus: Because of the cloud-based configuration, Chrome OS can boot within as little as three seconds. That instant-on capability is a large reason why Google describes the Chrome OS experience as more like using a TV than using a computer: You press a button, and seconds later, you're doing your thing.

Security is another expected advantage. Since you aren't storing data or running applications locally, the odds of contracting a virus are significantly reduced. In fact, the Chrome OS won't even allow applications to make changes to the operating system if they want to -- and, on top of that, the OS will continually update itself and correct any corrupted modules automatically. The critical pieces of the OS will also be stored in read-only memory.

Do you actually save any data locally?

Not much. Chrome OS will store a small amount of data locally, such as your system preferences. Even that data will be encrypted, though -- and synched with an online storage center, too. The idea, as Google explains it, is that you could lose your Chrome OS system, go get another one, and have everything back exactly the way it was within a matter of seconds.