* :

I heard that it's actually better to get 2 single core Xeons b/c to get
the speed out of one dual-core you need the software written for it,
and currently there is not much available. What are your thoughts?

That's BS. Software can't distinguish if it's running on dual core or on
dual cpu. The distribution of the processing load is job of the
operating system. If software is not multithreaded it never ever will
make use of multiple cpus or cores.

Benjamin