I was there from the get-go (put the public beta on my iMac DV) back in 2000. Then got the white box with the blue gel "X" in when it came out the following spring. I still had to use OS 9 for most things, but I found myself booting into X more and more as time went on.
When I bought my iMac G4 in March 2002, the first thing I did was yank OS 9 (System Folder, Applications OS 9, etc.) off the thing and run straight, undiluted OS X. When I decided it was time to "go X", I fully committed and didn't want any aspect of OS 9 to lean on, cheat with, fall back to, etc. When autumn rolled around, I happily stepped up to Jaguar (again, removing all traces of the vile OS 9 from my system).
A year-and-a-half later, straight Panther on my PowerBook, and eagerly awaiting Tiger's release...
Happy birthday, OS X! You changed everything...for the better.