imported post
When you hit the delete button on the PC, it only removes the first letter of the file name, which tells the PC that the file is deleted and in your wastebasket. The file is still there until the sectors on the drive are overwritten by another file. Even so, some years ago, I was advised that a certain government agency had the ability to take a hard drive or tape backup that had been erased and overwritten 14 times and still recover data from the first write. I suspect it is very expensive and labor intensive to do this and conversations with police lead me to believe that this capability isn't routinely used by law enforcement.
There are software products that wipe deleted files from your hard drive in a manner that makes them basically impossible to recover. Even if you don't need to evade prosecution or the guys in the black helicopters, these programs are good for keeping your hard drive clean, removing unwanted cookies, and temporary files that Windows does a poor job sometimes of removing when they are no longer needed. Cleanup is one such product:
http://www.stevengould.org/software/cleanup/. From a privacy standpoint, you should keep your hard drive clean.
With regard to "wardriving" I would definately recommend securing your wireless network. While I have never tried this myself, I once overheard somebody at a trade show tell another that if he wanted to download copywrited movies or music, he would simply fire up his laptop, drive around until he found an unsecured network, download the files to that computer and then copy it to his laptop. If the copywrite police ever tracked that download and filed suit against the downloader, they would be going after the unfortunate owner of the unsecured network, not him. I presume the same thing can be done with porn, kiddie porn or other unsavory stuff.
