Also, everyone that has a Hotmail (or MSN Passport) should link it to their XBL account. This allows you to monitor your buddy list using MSN Messenger, and eliminating the need to occupy your Xbox by signing on.
The MSN Messenger component can be set up to provide alerts when people sign in (like in DeadAim, if anyone uses that), send you an invite to a game, or sign out. It's very useful, especially while you're surfing the boards.