Having just the right name for your character is a very important part of building your identity in Guild Wars 2. In the dust of the Beta Weekend Event ArenaNet hit up the blog to offer a friendly reminder:
We’re building our Guild Wars 2 name reservation list on July 31. We’re only reserving character names from active Guild Wars accounts, which is why you’ll need to log in at least once before we build the list in order to be considered an active Guild Wars player.
If you have the original game and want to reserve a particular name for GW2 you’ll want to make sure that you’ve logged in and claimed the name. This only applies to two word (or greater) names as the original Guild Wars requires at least two names. Single word names will all be up for grabs during the pre-launch and on launch day.