Comparing hardware costs (whatever you might think of how they've done it) doesn't really hit at the problems of running a mainframe and the TCO involved. 1) S

Comparing hardware costs (whatever you might think of how they've done it) doesn't really hit at the problems of running a mainframe and the TCO involved. 1) Single supplier. Have a falling out with IBM.... you're stuffed. that's a major business risk. With x86, don't like HP go to Dell etc. 2) Staffing! What's the relative availability of good S/390 admins and devs, compared to x86? IMHO one of the reasons first mainframes, then AS/400, then proprietary Unix lost out to Linux on x86 was ease of getting staff, which is fuelled by the fact you can start out with a home PC and learn the kind of skills you need.