I have tried everything to rid my HD of windows 7. I installed my brothers copy on a new build of mine to run some tests and make sure the system was running okay. I did not think that I would have an issue installing windows XP. When I load XP from disc I keep getting an error telling me that I need a real copy of Windows XP. I have a authentic version, I have installed it many times before. I have read that downgrading from Windows 7 can be difficult. Are there any solutions I can try? I have already try installing in on a different partition. Same error. I have tried using the windows 7 install CD to remove windows 7. No luck. I even entered safemode in an attempt to delete WINDOWS and the system told me that they could not find WINDOWS. Any help??
Well if you want to completely wipe your hard drive, I highly recommend Darik's Boot and Nuke (free/open source military-grade hard drive wiping). Windows XP will not detect any previous operating system or anything
Also use DBAN if you ever sell a computer to completely blow away all of your data with no hope of recovering.
Make sure you back up anything you don't want to lose before doing this; there's no possible way to undo it.