AMD decided a while back to focus its expansion efforts on servers and notebooks. The result of this is that server chips are the first to get the improvements, and my guess is that after turion is launched, it's gonna take the no. 2 spot from the desktop. Anyways, AMD will beat Intel to dual core, but unfortunately for us it'll be 940 only for a while.
Anyways, I don't put much faith in the Pentium D. Prescott is a terrible core, and I think the dual core will run into more issues - in fact, with its huge die size, i think it might even have more problems, at least initially. AMD's 90nm cores are way smaller, so a dual core won't be quite so unwieldly, plus their shared cache won't take up as much space. Other downsides include a lack of the 1066MHz FSB (which should have been made available for non-$1000 chips), separate cache (it's looking like shared cache is more efficient, as it is being used in A64 and in future dual core PMs), and no hyperthreading; the latter means if you are looking for an estimate on performance, you have to scale relative to a non-HT P4.
I do however think Yonah looks promising. Improved FP performance, shared cache, better desktop platform, and, according to the inquirer, 64-bit support with socket 460, all make for the first intel chip i've been seriously contemplating for a long time. Of course, if AMD can keep up, I'll probably still go AMD, since usually I can get more for my money from them, but if Yonah is substantially ahead, then I'll gladly pick one up.