Vista loading CPU when idle

Is it normal for Vista to use about half of the CPU  when no apps are
running?

I have a 6 month old Dell that has started to show about half the cpu
consumed my the stuff that I have no control over that I can find.  Task
manager doubles the list of processes when I check "show all users" at the
bottom with some user called SYSTEM that I can't control.  SYSTEM  is the
culprit, and I can't turn anything off.

Anybody understand what to do?  I have checked the web and all I find is
registry cleaners that want money to deliver an unspecified solution.

TIA, pjl

Yes...

Yes... In Vista, Defragment and other maintenance is done while your PC and
CPU is idle... That's perfectly ok! It actually gives up the processing
power when you run any program...

Emil Lulic

If it's defrag change the schedule to run during the AM.

If it is defrag change the schedule to run during the AM.
Of course you would  have to leave it on.