Hello, I am looking to sell my current laptop. However I have used it for work and while I have never used it to access our customer data since its against the company policy I have used it to connect to our network. The company generally uses http://datakillers.com/ for hard drive disposal but don't require it for personal computers. Would a program be secure enough or should I just destroy the hard drive?
Extremely secure. As Hawkeye22 said, DBAN is a great utility. If I remember correctly you can even have it rewrite the entire drive with random data 35 times, although 1 or 7 passes should be more than enough. Obviously, a more permanent (and destructive) method would be to take it apart and smash the platters with a hammer. No one is going to take the time or expense to piece the platters back together and scrounge for data. The software route can still be read, but it is definitely difficult. It'd take some serious time and effort to get to the data after a pass or two, and if you really want to be certain, you can go for multiple passes necessitating your "auditor" to bust out their electron microscope.
Now, unless you're some kind of mob kingpin or spy, I wouldn't really worry about it.
Although DBAN is good, I prefer secure erase as I stated previously. Here are some exerpts I took from the link I posted earlier.
How does Secure Erase work?
Secure Erase overwrites every single track on the hard drive. That includes the data on “bad blocks”, the data left at the end of partly overwritten blocks, directories, everything. There is no data recovery from Secure Erase.
The National Security Agency, for one. And the National Institute for Standards and Testing (NIST), who give it a higher security rating than external block overwrite software that you’d have to buy. Update: There is an open source external block overwrite utility called Boot and Nuke that is free.
Secure Erase is approved for complying with the legal requirements noted above.