Administrator Password Recovery

Hello,
My PC has Windows 2000 Professional PC, and I uses a user account, but can’t install any program or do anithing interesting on it.
I do not know the Administrator password, it was set when the PC was in a netowork already gone, and nobody around here seems to know it. Is there any way I can solve the problem without formating the disk? May I find out which the Administrator password is, or promote my user account to Administrator without the Administrator passwrod?
Any help will be welcome.
Thanks.
Pablo.-