http://www.simple-talk.com/sql/performance/finding-the-causes-of-poor-performance-in-sql-server,-part-1/

http://www.simple-talk.com/sql/performance/finding-the-causes-of-poor-performance-in-sql-server,-part-2/

As for how you identify corruption, I answered that in the thread you started on tuning TempDB.

p.s. Please in future don't start multiple threads for the same problem, you just end up with exactly this, answers spread across several places.