The system was never shipped with the extreme edition CPUs, which draw appreciably more power than standard CPUs, so it is an experiment you'd have to try.  The first hurdle will be seeing if the system will identify the CPU -- it may not, and game over.  

Even if the system does identify the CPU, the next hurdle will be heat -- these systems ran hot when new and an Extreme CPU will exacerbate that issue.  And then you have the possibility that when new, such a CPU may work - but you're now running it on a system with voltage regulating chips that are in their teenage years.

You can easily buy a used system that will run rings around anything a system this old can do -- probably a better use of funds unless this is an experiment more than anything that makes economic sense.

There isn't anything.  The original CPU you asked about is second-generation, which definitely will not work.

The only CPUs that are faster are the XM CPUs -- which will have the same issue of using more power and generating more head, and which were never shipped with this model system.