You might have noticed, if you're a heavy user of PerfMon, that some counters are exhibiting alterations in behavior between SQL Server 2000 and SQL Server 2005. For example, I've long used the "Transactions/sec" counter to get an idea of how much work a SQL Server is accomplishing. Now, in SQL Server 2005, certain internal system processes and their transactions which were not counted the "Transactions/Sec" reading are not tallied. Consequently, I recommend that you consider looking at "Batch Requests/sec" as a better indicator of how much work is being processed.