If it was your work IT department, they may have instigated security measures built into XP Pro.
If this is the case, they would probably need to set-up a separate user account, for you to use at home.
The password you are referring to (I suspect), is a password for you to access your work server.
Can you please clarify, is the laptop a company machine maintained by them, or are you referring to it as a work computer, that is your own, but used for work? In which case, do you have administrator privileges?