Please see response below from Cyberlink, they appear to be very clear that if I only purchase the cheaper option it will not allow mw to have both versions on my PC?
Thank you for contacting CyberLink Online Support.
We understand your concern related with PowerDVD 8.0.
Graham, You can purchase upgrade to
Ultra 8 from my 7.3 OEM version at $54.95 and you can install that. But if you install the upgrade version on your PowerDVD 7.3 version, the upgrade will overight the 7.3 version and you will not have any PowerDVD 7.3 version installed on your computer and hence you will not be able to play HD-DVD on your computer.
And if you purchase full version of PowerDVD 8.0 at $99.95, you can have both the versions, PowerDVD 7.3, for HD-DVD playback and PowerDVD 8.0 for other disk playback, installed on the computer on the same time. And hence you can play HD-DVDs using PowerDVD 7.3 and other DVDs using PowerDVD 8.0."