Processor Clock Speed vs Cores/Threads/Cache

We are in the process of purchasing a new SQL Server. It will initially run 64 Bit SQL 2008 Standard R2 but we will eventually upgrade to 2012. It will have 48 GB RAM with RAID 1 OS, RAID 10 data and RAID 10 logs; all 15,000 RPM drives. The server handles the back-end for our (relatively small) 60 user in-house manufacturing system. I have been given the option of the following two processors:

2 x Xeon X5675                 6 Cores                 12 Threads          12 MB Cache      3.46 GHz
2 x Xeon E7-2830              8 Cores                 16 Threads          24 MB Cache      2.13 GHz

Considering the size of our system, would it be more beneficial (performance wise) to go with the faster clock speed processor (X5675) or the processor with more cores, threads and cache (E7-2830)? I.e. in our situation would SQL utilize more cores, threads and cache.