parallelism

[JOE TESTA]

We were discussing when to set degree parallelism on a table.  You experts out there, is there a number of rows that it makes sense to set it to something other than default?  I know there are times when parallel can be slower than serial processing but what is that threshold.  We are definitely setting it for the partitioned tables but wasnt sure if we should set it for other ones also.   thanks, joe