Cinebench is a widely respected benchmark for testing the performance of x86 CPUs. The program allows you to test single and multi-threaded performance as well as GPU performance by rendering with Open GL. Download here.
Super PI is a single threaded benchmark that calculates pi to a specific number of digits. Super PI is a single threaded benchmark ideal for testing pure, single threaded x87 floating point performance and while most of the computing market has shifted towards multithreaded applications and more modern instruction sets, Super PI still remains quite indicative of CPU capability in specific applications such as computer gaming. Download here.