How do you erase everything off your computer?

So I'm giving my laptop to my mother and I need to erase everything off. How do I go about doing that? I have Vista basic. Is there a way to do it without having to use the Vista CD, because I'm not sure where I put it...
Update: Let me just reiterate I DO NOT have the Vista CD or XP CD. I want to remove everything off the computer because I am getting rid of it and I don't want anyone to be able to find any of my personal info. I know how to remove cookies and uninstall programs I am wondering if there is an easier way to completely... show more Let me just reiterate I DO NOT have the Vista CD or XP CD. I want to remove everything off the computer because I am getting rid of it and I don't want anyone to be able to find any of my personal info. I know how to remove cookies and uninstall programs I am wondering if there is an easier way to completely wipe it clean.
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