how to change administrator password of Windows Vista. ?

I forgot my administrator password windows vista and I have only one user, which is the account of administrator. You know some tools to remove the password?

There are many tools that can do this, but most of them cost a lot of money. There are a handful of free tools, however. This page details five of them and describes their process: http://pcsupport.about.com/od/toolsofthetrade/tp/passrecovery.htm

20 – Administrator Password Recovery