Hi, Don,
One other thing to take into account, in your testing...
SQL Server insert/update triggers fire ONCE per insert/update statement, regardless of how many rows are affect. So if your single UPDATE statement affects 5 rows, the trigger fires once, with 5 rows each in the insered/deleted tables. You may already know this, but wanted to mention it anyway. (Some people code triggers on the assumption that only one row will be affected).
Kevin