text: windows xp installed twice? i tried to re-install windows. now i have it installed twice! how do i uninstall? wow! that's the first time i hear such an incident lol!  i mean, some computers have parallel operator systems (like having win 98 and xp on the same computer) but it's how you managed to make it happen in another way, cos windows usually tells you that it detected another os on your computer, and the only way to install the new one is through replacing the old one. no problem. you could uninstall one (technically you can because you installed when an os was already present...try 'add/remove programs' feature) the better way is to format your pc. don't forget to backup your files and folders to avoid regret!!