Here is the clear answer: Windows XP Pro, Academic and Regular retail versions, Upgrade and Full install versions, ALL require activation. If you installed the academic version (or another version -- they are EXACTLY the same), and it didn't appear that you activated anything, you may simply have missed it. Despite what the doomsayers have been spreading, if you have a constant Net connection, activation is incredibly quick and painless. You might not even know it happened. It took roughly 1/2 second to activate mine, and the activation process was part of a long series of "back/next" screens that were all part of setting up the software. It was a pleasant surprise that it was so simple.
But regardless, I assure you: This version DOES require activation.
I'm not sure why it's such a big deal, unless you're planning on using an illegal copy. Even if you don't have a net connection, you can still activate teh software just by calling a toll-free number.