I had CS4 upgrade on my old desktop and laptop. My desktop crashed. How do I install the CS4 upgrade on my new desktop without any prior Photoshop there to allow the CS4 upgrade?
All Adobe updates are FULL installers. They do not need to find a previous version installed.
When they don't find a prior version they will just prompt you for the old serial number as well as the new one.
Unless you still have the old desktop, you may have to contact Adobe customer service on the phone, however, to ask them to deactivate the version you had on your old desktop, since you presumably didn't have a chance to deactivate it yourself before the crash.