you dont even need to creat an account if you dont want multiplayer you just make a "home account" and never have to login or out its just like making a profile in any other game you type your name and jobs done
Though there are advantages to making an online account.
I reinstalled windows and forgot to backup my save games.
When I started up Dirt 2, and logged into windows live, it restored my game perfectly.
That didn't happen with Batman AA, another GFWL game, so I guess it's up to the devs whether they support that feature or not.