Trouble with clean XP install

My small consulting company recently bought five laptops at a bankruptcy auction. They are all in great condition running XP-sp2. The problem is that they are all locked with Administrator’s permission only. The old company’s tech guy is long gone. I have tried every way researched to change or delete the admin password, I cant even boot up with CD or floppy drive. So in effect, I can only use what is there… not make any changes. So Ive resigned myself to reloading XP from scratch on a clean HDD. Problem is, I get locked out from doing that as well. Can anyone help me out of this?