I have purchased the upgrade to Particle Storm 2. Does this mean I have two copies of PS (both old and new versions), and I can sell the old one?
Absolutely not! That is not the way any software upgrades work, which is why you get a big discount when buying the upgrade. When you install the PS2 upgrade, it references your old registration information and activates the new version with this same info. This includes the dongle info. Therefore, you can only run your new PS2 on the same copy of LightWave that you had originally installed. This also means that your original version of PS has to have been registered properly in order to be upgraded. But this should be an automated process, that if everything is done correctly, you won't even know that the procedure is being done.
Thor/TreeD