If I understand hyperthreading correctly, there is a possible advantage if one thread is floating-point intensive and another is integer-intensive.
Then two different parts of the CPU can work at the same time, giving speed increase.
But IV is mainly floating-point intensive, and you will probably see no gain.
On the other hand, maybe internet-browsing could be faster while IV chunks away in the background.
And supposedly sometimes, the CPU takes a performance-hit when hyperthreading is enabled.
The athlon still has a better floating-point performance, and I'll probably stick to AMD until Intel PROVES to be able to compete.
Dont believe all the hype you'll read about Hyperthreading.