1. Install win 7 normally, but do not enter the activation code - skip that step.
2. Install winows 7 a second time. make sure to have it overwrite the first instance. This time, enter the activation code.
I've done the same thing... I have a valid OS system license from XP and the windows 7 upgrade. But idioticly only used the upgrade on my fresh harddrive. Which activation code do i use on the second install of windows 7 upgrade? the activation code from the XP OS or the one for the windows 7 upgrade?