Thanks for the advice.You can start from the Snow Leopard Upgrade DVD without the use of an admin password or even the need to have the restore DVDs for Leopard.
There are also ways to reset the admin password, search and you will find.
Btw, it sounds a bit fishy, maybe the MacBook is stolen, as the missing password and the missing restore DVDs indicate. Is the power adapter included? The box and any other material that came with the Mac?