dual or quad core?

Its got dual-dual core processors which makes it a quad.

 

two duo core procs make four. see?

 

It has two processors (dual processor) each with two processor cores (dual core). There's a total of four processing cores, hence the quad core, and two processors, hence the dual processor. The difference between processor and core is significant.

 

There are 2 dual core Xeons.

 

Think of it this way

mac pro
aaa Logic Board
aaa /-------- \
aaXEONaaaaXEON
aaa |aaaaaaa|
aaacoreaaaaacore
aaacoreaaaaacore

 

That's a rather phallic way of describing things! Like everyone else has said, you're looking at 4 cores, which is a very good thing.