You can also slipstream drivers if your controller card, onboard controller card or controll were developed post SP2.
I'm not sure that Microsoft will allow you to replace your XP disk.
Old cd keys will not work on newer versions of XP.
MS seems to update their keycheck algoritms at every release.
Here is an interesting sidenote....microsoft has different cd key ranges that add or remove certain feature from the installation and windows.
Speaking of secrets......microsoft also has a set of secret menus that seem to be accessible through the run command....