Is it possible to use a dual processor computer as your desktop?

I've seen some people suggesting to get a motherboard that supports two processors and stick two Xeon Nehalem processors in it.

Could you use this system as a desktop PC or is this useless or even impossible?

It's more hypothetical question if Windows 7 would support such a set-up. I know you could just take an i7, but wouldn't two of those processors be a whole lot more awesome? Like the previous generation Skulltrails?

The idea would be to have a motherboard like this ASUS Z8NA-D6C Dual LGA 1366 Intel 5500 ATX and two Xeons (since I don't think i7's could be used) Intel Xeon E5405 Harpertown to run something like Windows 7 Ultimate.

Dual processor desktop. Is it possible? Yes.
Should you do it? -- don't bother unless you have custom requirements for it.

In fact, do not even go beyond Dual Core processors.
Do i7 and Nehalam architecture in general have advantages? yes.
Recheck your need for a multiprocessor setup and take the call.

There are a lot of other hardware parts you can use the money on.
Memory for instance: Dynamic, Magnetic or Solid State these days!

In normal desktop applications, the bottleneck is almost always I/O. So I'd say spend your money on one of those new Intel SSDs and lots of fast RAM.

It depends on the operating system you want to use. If you want to use Windows XP Home, I'd say it does not come with a multi processor kernel.

But the question is: Why would someone use a multi processor PC as a desktop PC? What about dual and quad core CPUs?

There is no reason why you could not... but beware that typically this might mean you need a whole bunch of components specifically suited to the motherboard too... from specific processors, to ECC memory, to in some cases, special expansion cards.

There is however a potential benefit in that multi-socket motherboards typically have a much better aggregate memory bandwidth than a multi-core-single-socket solution with the same total number of cores. Not to mention that there are usually more memory sockets meaning you can put a whole lot more memory in, which may make sense depending on what you intend to do.