228644 Need admin access unlock setup

I bought this computer online from what appears to be a college kid. I can only log on using a guest name. While in windows many things like Control Panel features and AIM,AOL are restricted. I can't change the ADMIN password without unlocking up setup in the F2 BIOS. I don't know what it is. I was told the CMOS battery trick will not work and have tried several things! It is not an easy task! If you can do it let me know!