Fishy or not, he's going to find a way to either reset it or to reload the OS.
It would have been helpful had you listed the operating system on the netbook. I'll assume it's XP or Vista. I did have need to do the same thing a few years ago. I used EBCD (Emergency Boot CD), it was free at the time but I believe the current version must be purchased. You might be able to find a download of the older version somewhere. There are other programs which will accomplish the same thing, Google can be your friend, this page turned up another alternative:
http://www.recoveranypassword.com/recov ... -recovery/ I haven't tried it so I don't know how well it works.
Basically you'll be burning a bootable CD which will allow you to clear the administrator password.
You probably know this by now, but never, ever allow anyone on your computer in an administrative account. If you must let someone use your computer, set up a limited account for them. It's worth the extra couple minutes it takes.