I have sold an old legitimate copy of windows XP with a desktop computer. I now want to change the installation code on my laptop to the code on my windows on the desktop as they both ran the same copy. I have bought a brand new copy of XP so the purchaser of the desktop and I do not have the same product code. I am told that it is possible to change the code without reinstallation of windows XP. Is is possible? And how?

XPPID - google :)

An alternative is to pm me if you are really struggling.

Thanks to venger and sheff_minx. Task completed.