I can type that code by memory still. Just like I have my Half Life key memorized still. Retarded huh? At one point I remembered my Windows 98SE key too but that was when I used to dual boot XP and 98SE back when gaming on 98SE still ruled.
I want to say that this version came out even earlier than the 35 days before Oct 25,2001. I remember people getting their hands on the Devils0wn copy during the 9/11 crisis.
Edit: Yup, Aug 28, 2001 was when it came out. I remember Win XP came a few days after my birthday. I woke up on my bday hoping someone released it already, but it turned out I had to wait a few days.