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Is it a clean install that you are doing? If so, I would use the partition manager in the install phase to totally remove your existing Windows 7 partitions and then create a new clean one and begin the install process again. If you have 3 copies of W7 on your boot menu then things are getting a bit cluttered
Your Windows Experience score of 1 was probably just because the test had not been run yet... although installing the NVIDIA drivers shouldn't cause a problem like that.