T43p: Security Chip

[slowfighter]

I wish to delete all content of Security Chip of my ThinkPad T43p (shopped at eBay in Germany) because I don't know the previous owner passphrase/password.
If I open BIOS Setup (just on first boot) using F1 (No Fn key... No Esc key!) I see in the Security menu the option Clear Security Chip... I think that I can access to BIOS as supervisor without any password... I hope! How can I verify?
Can I use this option to clear the Security Chip or I must know the old passphease/password to clear it?

Please help me... I don't want to destroy my ThinkPad!

Another question: How can I verify if there is the Predesktop Area on my hard disk?
Using Linux fdisk (Setting in BIOS Predesktop Area to Normal, Secure or Disable) I see just 1 partition... but if I press 'Access IBM' button on boot... it starts Rescue and Recovery.
I wish to understand if previous owner has lost this area...

[slowfighter]

Is there anybody out here?
Please help me... if you can