FSX ativation FAQ from MS.....

This may answer some questions.
http://support.microsoft.com/kb/927007/en-us
One of the important FAQs is:
"Q4: How many times can I activate the product?
A4: You can activate games for Windows two times. Removing and then reinstalling the game will not affect the game activation quota as long as you have not changed any hardware components on the computer."
I interpet this as meaning you can re-activate it as many times as you want as long as you don't change (major) hardware.
Otherwise you get to change hardware once and activate it before you have to call the toll free number to activate.
So, this is basically like activating XP.
http://support.microsoft.com/kb/927007/en-us
One of the important FAQs is:
"Q4: How many times can I activate the product?
A4: You can activate games for Windows two times. Removing and then reinstalling the game will not affect the game activation quota as long as you have not changed any hardware components on the computer."
I interpet this as meaning you can re-activate it as many times as you want as long as you don't change (major) hardware.
Otherwise you get to change hardware once and activate it before you have to call the toll free number to activate.
So, this is basically like activating XP.