Hello tom32,
Just a piece of advise when reformatting your laptop. Make sure that you have saved your important files in a separate drive. If you have a partitioned HDD then that's good. You can save your important in a different drive, that is if you are only reformatting the drive on which your previous OS is installed. Second, you need to download or prepare the drivers of your laptop hardwares. All you need to do is insert the Licensed Windows XP OS in your CD Drive and you are all set. You just need to follow the instructions for the installation of the Windows XP OS.
I hope this helps.
Thanks,