Before I ditch my old computer

[DawgHouse]

I have an old computer that I need to either donate or sell. It's just sitting around gathering dust. I've removed all the files that I needed to keep. Is there a way to clean the hard drive before I sell it? I just want to make sure there is nothing personal left on it that might fall into the wrong hands.

[RoyGBiv]

1. Depends ...

If by "personal" you mean a letter you wrote to a significant other at some point that would only mark you as a hopeless romantic, then you could make certain enough that the files were sufficiently destroyed using a disk wiping program that adheres to DoD standards. Eastec Eraser is one such program for an MS platform. It's commercial, but it's fully functional for 30 days. It will take a long time to wipe a disc safely of any significant size, so be prepared for that.

However, if by "personal" you mean anything else that might compromise financial records or otherwise cause you a great headache, I'd personally go for the "donate without hard drive" option. The only safe way to destroy data permanently is a three step process. After removing the drive from the machine, you take a sledgehammer and beat it into as many parts as you can. Then, you find a blowtorch and melt the platter until it achieves a gooey state. Finally, call a Hazmat unit or find how your community handles disposal of potentially dangerous waste. At this point, your data is gone, and barring time travel, no one will be able to recover it.

Chances are such drastic measures are not necessary. The DoD standard wipe you can do with the previously mentioned program will work.

N.B. The real DoD standard for state secrets involves the blowtorch method. Nothing is permanently erasable for a person with the right resources and a determination to recover data.

[Berserker]

2. Here is a great

and free little program that may meet your needs. I use this program daily to erase not just delete files. They only sure way to keep data from being recovered is to destroy your HD.
But unless you really have something to hide this will do.
Eraser is a secure data removal tool, which allows you to remove sensitive data from your hard drive by overwriting it with carefully selected patterns.
http://www.tolvanen.com/eraser/