While you're logged into your Account Management page, don't forget to create your BattleTag. You can choose this permanent account-wide nickname by clicking on the BattleTag "Create one now" link on the left side of your main Battle.net Account page. Choose your name wisely, as we currently only offer one free name change. A BattleTag is required to play Diablo III, so whether you get into beta or not you should pick one while you're there.
Keep in mind that with such a large amount of invites for our test hardware we fully expect a strong possibility of stress test issues, such as an inability to log in, disconnections, and potential lag/latency. We'll also be testing our queuing system ,which you may see when attempting to enter a game.
Thank you for your continued help, feedback, and patience as we approach the May 15 release.