Wait, what is your goal here, a full install? What you should do is load up boot camp and you should see an option to get rid of the windows partition, correct me if I'm wrong. Then you will see the HD is now a single drive, then reintsall the whole bungsquata.
EDIT- What I mean is go into OS/X and go to Applications -> Utilitys -> Boot Camp, then you should see an option to rid ur windows partition.