My CPU Usage please help! PLEASE READ THIS SUMONE!

My old computers parts too old to run games at good fps... Make sure you note before i bought the new Mobo, New ram, and new processor my cpu usage did not jump like this.. The problem is that i bought these new parts put them in updated them and everything... Note I have no viruses or spyware and i have no anti virus running power suply 500w my cpu usage on desktop is usaly at 0% but randomly when im doing nothing it will spike to around 100% for a short amount of time when this happens everything on the pc become chopy and slows down untill the cpu usage goes back down to 0, Btw i have freshly reinstalled vista. I thought my hard drive was about to die on me because when this happens the hard drive started flashing and loading stuff.. but even on my new hard drive this still happens... So if anyone can tell me whats causing my cpu usage to spike to 100% like this randomly on desktop when nothing is running at all when its at 0% it will randomy spike to 100% this happens when im playing games too and even when im not playing games just sitting looking at my desktop i have 48 processes running which is normal for vista iexplorer.exe uses up 26,064kb and explorer uses 14,216kb