Hyperthreading was ahead of it's time. Back then apps were not multi-thread aware, so it offered no real benefit. Of course today there are multi-core CPU's available.
Hyperthreading does not offset the real world performance advantage the Athlon XP has over the P4.
At the end of 2004, my cousin and I both built new computers. He built a system around an Athlon 3500+, I around a P4 550. I figured with an over 1GHz advantage, give or take a few MHz for overclock, I would come out on top. The systems were roughly comparable, but every benchmark we ran showed his system to be faster.