Unusual CPU usage by ‘System’, what to do?

I was having problems with my svchost eating up 99% of my CPU (Windows XP, Dell Latitude D600), so I disabled Windows Automatic Update, and that solved the problem. But now occasionally my CPU usage will increase to 100%, a majority, anywhere between 40-95%, being taken by the ‘System’ process, listed in task manager. Whats going on? What can I do about it? What exactly does this nebulous process do? Ive used several antivirus programs and found nothing, nor have I found spyware or Adware. And I don’t plan on switching to Apple or Linux, for those of you who might suggest it. Any ideas?
Like I said, I tried cleaning up adware and spyware, and I delete my cookies regularly. I notice the problem gets worse when I run iTunes.

might just need to clean up ur cookies and adware u be surrpise what in there my advise is run cleanner get it for free and here more info and the download site http://www.stevengould.org/software/cleanup/

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