My iMac reports that all Boinc projects utilize up to 98% of each of the two processors. My Vista laptop reports never more than 50%. Is this the basic difference between mac and pc processors, or...?

It sounds like you have different preferences set on each machine, or the preferences are interpreted differently... What kind of processor does either machine have?

IMHO, 50% on your laptop is probably right where you want it because of heat dissipation issues. I run 100% only on my desktops, and 50% on my laptop--killed one a few years ago when running at 100%. Melted some of the plastic, and killed some of the components near the CPU. It was a mess, and since then I don't trust all that heat in such a small space.

I don't have an iMac and no multi-core machine either, but I think it's only the point of view:
the iMac reports percentage per core, Windows per system. I.e. each core contributes 50% of the system power, which results in 100% :-)

Gruß,
Gundolf

If your host has two cores, and you look in the processes list in Windows task manager, 50% means that it is using a full core. Mac probably identifies usage as 100% == 1 full core.

Now that makes sense. Thanks to all for the input...

and on a slightly used V8-server you will see up to 192 hours on the idle-process each day.

windoze task-manager is core-orientated, not machine....