MHz ratings tell you little about the actual real world performance of the CPU so yes, he's right. The numbers in the model number mean nothing, it's just that, a model number. Horza was also right about the original reason for the xxxx+ AMD model numbers, they were supposed to compare a product to its comparable Intel product. Right now, with 64bit multi-core CPUs it means nothing, the numbering scheme no longer works for current technology.
hakgipc: You've asked a very similar question before, the answer to your question is no, 5000+ does NOT equal a 5GHz CPU in any possible way.