Same HDD or a secondary one? With HDDs as cheap as they are, I would recommend buying and installing another HDD just for your XP x86 installation, it is just easier that way. Also, and correct me if I'm wrong, but if you already have Win7 installed, you may need to format the current HDD in order to repartition it into two separate primary partitions. And depending on your computer specs, it may support XP Virtual Machine, in which you can run older programs.