Did you know that your installation of Leopard comes with a built-in performance monitor? It’s called “Instruments” and you can attach it to any process currently running. In the screenshot you see here I attached it to an instance of Eclipse while running some unittests.
Instruments has some nice templates for you to choose from, and you can monitor CPU activity per thread, disk I/O, User Interface activity, Object allocations, and leaks. Just so you know, it might come in handy.