I own a HP laptop which recently had its mother board replaced. The machine came with an OEM installation of MS Windows Vista - I didn't reinstall / remove but I did lock out and changed the password for the 'Administrator' account. To my surprise when the laptop came back from repair (official HP on warranty repair) the Administrator account was unlocked and the recent activity on that account indicated that video files were being run recently from it.

I assume that they must have a way to unlock the account I just hope it's not a full time remote control like mentioned in this article. You can be sure of one thing - I will never buy from HP again.