I am new to using a Mac and using Parallels. I installed Parallels 4.0 on a MacBook. I then installed Windows 7 Home Premium upgrade. The installation went fine until I got to the point where it asked me to put in the product code. It would not accept the code because I was using an upgrade version instead of a clean install. I did choose the custom option when I did the Windows installation. Since it would not accept the key, I left it blank and the installation completed. Now I am trying to activate the software, but it still will not accept the key. Any suggestions on how to get this to work would be greatly appreciated. Thanks.