I am planning on selling my Dell Computer that has windows xp installed. I have had this for about an year.
My question is, since all these days i had so much of private information on this computer how do i delete all of the files so that they never can be retrieved.
If i just delete files and sell the computer, files can be recovered. The only way they cannot be retrieved is if i do a format or even better low-level format. However, i do not want to mess up my existing windows xp and other other softwares.
Which leaves me with only one choice. Delete the files "somehow" so that they cannot be retrieved.

Hope i made my query clear.

Thanks in advance.