2010, 27 iMac. I am in the process of installing Windows 7. I understand that I have to have one partition in the internal drive with one system X installed. After Windows is installed, can I create an additional partition? I want to use also 10.9 and 10.6, so it would be a total of three partitions. I had 10.6 and 10.9 in the main drive. I cloned both of them and now I am working from an external drive.