This is a very useful thing but it is not well known.
Step 1: Logging on
Turn on your favorite internet browser. Now log on to www.xbox.com, now look you need your Windows Live aka your hotmail info i.e. password.
Step 2: Loging in
Ok so now here is where you need your hotmail info, now if you don't know you need the same info that you used to sign up on Xbox Live. If you forgot it then your screwed. But there is a solution. REGISTER FOR A NEW ACCOUNT AT HOTMAIL.COM. then you can go on your Xbox and change the info.
Step 3: VIOLA
Ok your done now poke around and you should find some very useful tools.