os problems

I have an old laptop that was given to an employee for work. this laptop has an unauthorized xp os on it. i need to re-install the original win 2000. so i need to format the hard drive. i have done many formats to win98 systems but from xp to 2000 im not sure what the best technique is. i put the reinstall cd in but xp disables it. i found a win 2000 boot disk but that does not seem to work. any ideas? thank you in advance for your time.