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