Change owner's username

My uncle gave me his laptop. It has windows xp on the same. I am looking for some way by which I can change the owners name in that. I checked inside all the settings but still cannot find any option. Is there any file stored in the pc which I can edit and add my name. Or is there any tool available that can help me to edit the same. I tried various thing but nothing worked here. Can anyone tell me the registry location.

If you are talking about the user account then you can do that by creating a new one from Control Panel > User accounts. You can create a account with full admin privileges and then simply delete the old one. In this way the account name will be changed. You can also change the computer name by right clicking on My Computer > Properties > Computer Name. Just modify the old one and reboot your pc.