Yes, they do.. All the newer Xeons support
HT...
I think once you get your system put together, you will be very pleased with its performance. I used to run a Dual MP2000+ on a Tyan S2466N-4M and this thing was fast under SMP applications. However, my Xeon Dual 2.4Ghz 533Mhz is much faster. Noticeably faster on the applications I use due to the HT, SSE2, and 533FSB..
Here is my system
Which Xeon 2.4Ghz or 2.8Ghz processors are you planning to use? There is a 400FSB and 533FSB. To utilize the 533FSB, your motherboard will have to be 604pin compatible... The 603s are for the 400FSB...