Well, just to let you know, the P4 was never designed to go Dual. The HT is "supposed" to give the performance of a dual chip setup with only one chip. That is really not the case. After the P3 the only Dual boards were slotted for the business side of the world. As Dual processing really doesn't help the consumer much, the dropped it. AMD is the only compnay creating Dual chip for the consumer market.
Now if you want to go back to the P3 I can recommend a ton of good boards and provide additional information for you, but the P4 is a no go. Th only way is to get a Xeon. You can get a really high end workstation put together with some amazing chips if you spend the money. Dual or quad, what ever you want. And then even toss on a for hunk of Ram (8 GB) if you feel like it.
Just dreaming now...
Sorry to burst you bubble...
