The cpu load would pulse from 1-2% up to 10-12%-load with about three-five seconds intervals...(in idle)
The jerking has not been due to low perfomance hardware or old drivers and I have had the problems on two seperate systems.
If you are connected to a LAN and have similar problems, this might be the solution:
3.Click on "Device Manager"
4.DoubleClick on your NIC under "Network Adapters"
5.In the new window, select the "Advanced" tab
6.Select "Connection Type" and manuelly set the value of your NIC. (Not "Auto Sense" which is default.)
7.You should reboot...
On my systems the "jerking" in 3D games was completly gone, and so was the high idle cpu load.