Good tool for simulating many threads doing INSERTS UPDATES SELECTS and DELETES on an ODBC database? I've done load testing on a web application already using tools like JMeter, and tested my database for transactional integrity.  

But are there any tools for testing an ODBC connected database (like MS-Access) using just the database?

I'd like to be able to simulate a real world situation of multiple connections reading and writing to and from the database.  I want to use this tool to prove something will work before I put it into production.
The IT shop I work for "bleeds blue" (ie, sticks mostly to IBM tooling), so the performance software we use is IBM's Rational Performance Tester (RPT). IBM's stuff isn't (usually) free or cheap, but RPT has helped us to populate our databases through our applications (mostly because the relationships among the tables is too complex to do nicely via script).

That being said, we are also considering using a tool like the following data-generator, in order to better be able to mass insert data into our database for performance testing.