I'm on a single-processor 15" 1.5GHz G4 Powerbook, on OSX10.4.2.
I repaired permissions last week, and that's the first time I've ever seen anything like that. I'm pretty sure it was just a one-off glitch with Activity Monitor and MS Update installer. Current CPU usage is about 15% now
The AutoUpdater took forever to check for updates, and the MS Crash Reporter always seems to crash when Word crashes
So, I'm pretty sure it was a fault with the MS Software.
It was writing to the HD at that point, at about 30Mb/sec.
I posted that more as a humourous thing, rather than a "help!!!!!!!!!!" thing