Important clarification to add: Processor vs Core Microsoft definitions 

Page shall contain the exact definition of what a processor is, microsoftly speaking. Indeed, this concept is quite blur if we refer to the numerous pages from different Microsoft web sites.

For instance, at http://www.microsoft.com/technet/windowsserver/evaluate/features/compare.mspx, we can find:
Windows 2003 Server Standard x64 R2 (64 bits):
- 4-way symmetric multiprocessing (SMP) support

Other example for the same Windows Server 2003 R2 Standard x64 Edition at http://www.microsoft.com/windowsserver2003/64bit/x64/standard.mspx
- memory-bound applications that do not require more than four processors.
- supports up to 32 GB of RAM on 1- to 4-way servers.
- Windows Server 2003 R2 Standard x64 Edition supports up to four CPUs on one server)

If we refer to Wikipedia, http://en.wikipedia.org/wiki/Symmetric_multiprocessing, multiprocessor architecture or multicore processor are both SMP architecture. Thus, by speaking sometimes about 4 processors support, sometimes about 4-way SMP support, Microsoft confuses us all.
Coming to a Quadri 4-cores based server (16 SMP), this leads to go from a Standard edition (4 processors support) to a DataCenter edition (4x4=16 SMP support), thus raising the license price as for no less than +700%.