Earlier then that actually. I recall, ugh, Windows XP 64 bit, on the original Athlon FX-51 that my friend bought. Which says Sept 2003, and I believe we had a LAN party that winter since he graduated high school the next summer. Talk about early adopter. We had so much trouble getting that thing to play games over a network, really bizarre. I recall Unreal Tournament having a hissy fit, it was like he was playing 2 frames to our 1.
Then our other genius friend bought into Rambus on the Pentium 4. Instant regret.