About the Shield its on standard,The actual CPU usage is small. But if you do use vista there should be an program called the Performence and Reliablity monitor in Control Panel>Performence>advanced.
I don't really know much about CPUs and Treads but "System"(Kernel and NT) is listed using 130ish treads.
The Monitor shows 2 lines one green one blue
http://technet.microsoft.com/en-us/library/cc722173(WS.10).aspxThat has a table which makes it abit clearer.
Now the green line isn't doing much most of the time, but the Blue is always at Max.
My HDD seems to have clamed down for a bit today were the Blue line for the HDD graph dipped down for a bit.
Another issue that comes to mine is that, The "Cached" Space on my Ram is constantly filling up without Superfetch, I know that This could be just windows.
Specs
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AMD x4 2.5Ghz Quad
6GB Ram
750HDD
NIVDA Geforce 9800GT(1GB RAM)
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Vista service pack 2 64bit