Q:

X5687 vs X5690 CPUs for a SQL 2008 R2 Server

I have the choice between:
2 x X5687 (Intel® Xeon® Processor X5687 - QuadCore
(12M Cache, 3.60 GHz, 6.40 GT/s Intel® QPI) 
or 
2 x X5690 (Intel® Xeon® Processor X5690 - SixCore
(12M Cache, 3.46 GHz, 6.40 GT/s Intel® QPI)
for a new DB Server (SQL 2008 R2 64bit), my personal preference is X5690, are there reasons that would speak against going for a SixCore CPU vs. a QuadCore CPU ?

A:

For 2008R2, I'd take the extra cores every time. 
If the server might be upgraded to Denali/2012 on release you may need to factor in the switch from per socket to per core licensing. @MrDenny summarised this well in SQL Server 2012 Licensing Changes.

