Tools to Replay Load on a SQL Server
You can replay a SQL Server Profiler trace against another server using the SQL Server Profiler itself.
See the following Microsoft Reference as a starting point.
http://msdn.microsoft.com/en-us/library/ms189604.aspx
Quest Software also have a tool called Benchmark Factory that can be used to perform SQL Server load testing.
http://www.quest.com/benchmark-factory/
One of the best tools is actually freely available from Microsoft. The RML Utilities are targeted at SQL2005 & SQL2008 and are specifically designed for this type of testing.
You can download the tools from http://www.microsoft.com/downloads/details.aspx?FamilyId=7EDFA95A-A32F-440F-A3A8-5160C8DBE926&displaylang=en
We have used them to solve several performance and locking issues.
Note: Capturing trace files using the SQL Profiler GUI can add to performance problems due to the way the GUI and Trace backend interact. The RML Utilites include a script that can capture traces directly from the SQL Server without using the GUI.