Well ... you missed a lot.
The XP beat the P4 at every single edition.
The P4 never was better at multithreading than the XP.
The P4 was a clear loser for all of its existence, but it was justified by Intel marketing, which also convinced you obviously.
Now maybe some of the 1000 bucks retarded models had no match on the AMD side because AMD did not care (and I'm not even sure of that) - but the sure thing is there was no good reason to buy Intel.
You also have to remember that Intel started the P4 with that dumb RDRAM idea, which they eventually dropped - but for a while it was RDRAM or SDRAM and nothing else, all the while Athlons enjoyed DDR and then DC-DDR etc.
The fact of the matter is, for the whole athlon XP era, there was no competitive offering from Intel and every single pc sold should have been built with Athlons. (Oh and for those who OC, you know how the intel core series OC'd decently ? well some guy did a +100% OC on Athlon -- it WAS a really good chip - in it's time the equivalent of the C2D when it started )
Here some links from Anandtech (disregard the conclusion, as Anand clearly overweights "content creation" and "encoding", which we all know are somewhat irrelevant for 99% of the population, unlike gaming and office productivity):
http://www.anandtech.com/show/835/13
http://www.anandtech.com/show/1066/30
And yet .. that is all without mention of the price, which was a huge win in favor of AMD.