If you have ever had personal information on it, and especially if you've had financial information on it like from Quicken, I would stripe the drive before selling it. Unlikely, but someone could recover your data. Do a web search for 'disk striping software'. I found one last time I sold a pc that gave a short trial period which was enough to stripe the drive. You'll need to reinstall windows after that though which is a problem if you don't have the cd's.