Yesterday I downloaded the rc version of Windows 7 to my Apple Macbook pro computer and could not open it so I dumped it from my computer. I have parallels installed and will set up a virtual computer in it. Can I reload the windows program operating system again. {I also have a key code}?

The simple answer is yes. I take it that you were not trying to run the ISO file and that you burned it to a DVD using an ISO burning program to make a bootable DVD. If, after you install it again, it does not accept your present validation key another may be obtained simply by going to the MS dowload site once more.