I rely on LastPass for confusing sites like that one. If it weren't for that addon, I'd never know, for example, which of the 7 or so Windows Live accounts that have been generated on my behalf is The Right One for which website.
I merely bought and installed an xbox 360, and now I have a small number of windows live or hotmail or xbox accounts, I haven no idea which are distinct accounts and which are linked in some way. Ptthht, ptthht. Trying to cancel the auto re-up of their gold account was a nightmare of circular hate. Ptthht.