Far from it, the Xeons have better power decoupling, better SMBus support and much better thermal management (since the HSF can fall off and the system will stay up).
As for DIB, The Xeon has it, the Athlon MP does not … the Athlon does, however have dual FSBs (one per CPU). DIB refers to the Intel habit of placing the CPU on the FSB and the L2 cache on the other side where it goes through the CPU’s bus controler to get to … this leads to two independent paths to and from the CPU, one from the FSB at FSB clock and 64 bits and one from the L2 cache at full clock and 256 bits (the backside bus, the nomenclature goes back to the Slot 1 where the front and back side of the cartridge ran different busses). The Athlon has the L2 hooked into the FSB and then the L2 into the CPU, so all data goes over the 64 bit full clock bus.
There are plusses and minuses to two FSBs, the plus being higher bandwith (going away very soon with Xeons getting 533 MHz FSB) and less bus contention, the minus being it takes longer to perform a cache snoop (there’s another hop, the northbridge, on the way).
And, BTW, the Itanium at 1 GHz is 20% faster at FP than the Sledghammer at 2 GHz. I think that’s a bit of an advantage, especially since the Sledgehammer is running on .13 at 2 GHz while the Itanium is just being moved (shortly) to .13, but is right now running at .18 microns. Intel also has working .09 micron parts already (they’ve had them since before the t-bred), so the clockspeed advantage goes down the drain very quickly indeed when Intel shrinks the die. Oh, and Itanium isn’t EPIC per say, EPIC is just Intel’s brandname for its particular VLIW code. The other notable VLIW chip is the Crusoe.
PS: the rest of my software costs money too, a copy of AutoCAD is $1000 for IA-32 and compatibles, for IA-64 it’ll be about the same. Windows XP costs a bit more, but it’s not prohibitive.