I want to move my Photoshop CS5 installation to a new computer.
Unfortunately, I lost the paper with the cd-key.
Is there a way to recover the serial from my local installation?
If you logged in with your Adobe account when you first used the serial number, I believe it gets tied to your Adobe account and is retrievable through their website.
Use a regedit reader specialized for license keys,for example :
LicenseCrawler (free, portable)
The Magical Jellybean Keyfinder (has free version)