The down side to purchasing used computers is that there are a lot of unknowns, and there is almost always some work that always needs to be done to make them usable again.
Passwords are there for a reason: to protect someone's data. The previous owner could be deceased or simply wasn't computer savvy enough to wipe out his data before selling the laptop.
That aside, as the new owner, your BIL will no doubt want to have a clean slate to work with. I would first use a boot disk to format the drive. You can use any existing computer to create one. Some PCs will also allow you to format the drive from a system setup screen that is accessible during boot up. It usually involves pressing F2 or F6 during the power up sequence. Whichever key it is, it will say so on the screen (although it will probably flash by very quickly).
Once the drive is formatted, the next thing he would need to do is reinstall the operating system. If the laptop didn't come with an OS disk, then BIL needs to chalk it up to caveat emptor and go buy one.