Windows Vista vista administrator password

Hi guys our family recently had a death in the family due to suicide and my sister is just wanting to go through my brothers laptop for some answers to why this happened,he had a password on it with a hint but the hint means nothing to any one of us.I know how to do this on xp with a command prompt and ive tried the same method with the vista laptop but to no avail i would really appreciate any help so as to answer any questions that we have as to why this happened many thanks Nicky