pentium D with HT = Pentium D EE 840...dual core.
and you better be comparing it to the Athlon 64 X2...
in that case, X2. not looking at the price...its overpriced IMO, but still a nice CPU.
Go with a sempron, one of my friends has a Sempron 3100+ and its pretty darned quick...i also have a friend with a Celeron D (the 2.8 GHz model...whichever one that is) and it didn't impress me at all...AMD all the way (though i admit i AM biased toward AMD)