If you were building a new house, you wouldn't frame the walls with cardboard. You wouldn't install floors made out of Styrofoam and bubble wrap. If you use short, simple passwords, you're guarding your files and sensitive information with flimsy security.
The longer a password is, the more secure it is. When you create a password, think of a favorite phrase, quote, or song lyric. For example, “StairwaytoHeaven” is a really secure password.
For added security, throw in some uppercase letters, a number, and a symbol. "1StairwaytoHeaven!" would take a modern desktop computer 71 quadrillion years to crack!
Try to make all of your passwords unique. If you have trouble remembering passwords, use a password manager like KeePass or Roboform.
Remember not to lose or forget your master password. The Help Desk may be able to reset some of your passwords, but they won't be able to recover master passwords.