I just received a new Mini and a Parallels 7 disk. I ordered v 8 but 7 came? Is this upgradable to 8 free? At any rate how do I install 7 or 8 without a disc drive? I have 3 Win 7 machines with DVD burners, a 16 gig SDHC, and an external HDD. Any suggestions? Should I just download it and use the registration code on the CD package? Thanks.