I bought a used computer and don't have original owners password to get into windows - what can I do?

the computer was bought at a yard sale. It has windows xp on it but when I try to get on it wants a passward that I have not been able to obtain. what are my options?|||Could you go to where the yard sale was and ask for the password? If not, I'm sorry, but this is a good one. You would think they would of taken the password off of the computer before they sold it. Or as Lemuel G said, reformat it, that is one of the ways of getting past the Windows password.|||call them up or go back to the house.. but there's other ways|||if its from a yard sale, you may want to start new and reformat it, its the only work around on the pasword problem|||format. Get your own Windows XP cd and at startup put the disk in, then the computer will startup and do some stuff, then it will prompt you to press any key to continue. Then format the computer and then install windows xp, this should be easy and you will figure it out when you do.|||call the people from the yard sale, if that doesent work open the tower up and remove the battery from the motherboard, and put it back in