writes "As I start considering a new computer, I find myself facing a peculiar concern. How do I decommission my old machine? In the not-too-distant past, I would make sure I backed up my data and then I would wipe the drive before selling it/trading it in/giving it away. These days, it's not so easy. I have to de-authorize my iTunes Store Account, my Audible Account, my Sony Reader Account... but what else? There are tools, utilities and applications that I don't use very often. I know that some of them required some kind of registration/authorization during the install process but I never considered keeping track of that sort of thing over the last couple of years. What will happen if I forget about one? I'm sure there are Slashdotters who have already dealt with this headache. Which vendors have you found helpful and which vendors have you found uncooperative?"