Thank you for your answers to my questions.

I understood you about what "3 disk" means... well, in this context I wanted to mean three allocated RAID-protected arrays on a SAN (3 independent already protected LUNs or Volumens). So, according to GSquared could be better the option b:

b. One LUN for database files. one LUN for log files including the tempdb log file. One LUN for tempdb data files.

I know that is better to take a baseline before to worry about to where to put the tempdb files on a production server, but what about the best practice to install a new production server. I would like to take the best decision about this. Regarding to capture performance metrics from your production environment about tempdb contention and performance, which ones are the best metrics and performance counters to use in order to decide if the tempdb is or not suffering to much workload??

Thank you.