Starts & Stops: "Not Responding"

I am experiencing a constant and most annoying issue with my new computer with a new Ultimate x64 Vista install. The thing just "Hangs." I can be going along, often in a browser, either IE7, now 8 and Firefox, or in other programs and such, and the thing just stops. The sidebar CPU meters will be slowed and the graph drops to the bottom, the Network Meter activity drops to the bottom too. Often the background stops but not always and the same for the second hand on the clock. The circular Aero spins and the windows are unresponsive, often the window is reported as "Not Responding" and if something does respond to a mouse click only the button moves but any corresponding program action doesn't happen.

The thing will then just sit there like this for half a minute, a minute, sometimes a minute and a half, and then suddenly eveything starts running again and zooms right along. Till the next time which could be the next time I click on something or a few minures later, or longer or shorter. I am coming to my wits end. I am almost beginning to believe the Mac guy on the commercial. I have downloaded and run the System Info program.