How to disable WinSAT.exe in Windows 7?

I just had a strange behaviour on my Windows 7 box. Some minutes after unlocking my workstation the aero theme changed to basic, the hard discs were working and the cpu consumption was highly increased.

To analyze the behaviour I did the following:

• First I started task manager and selected the process tab. Nothing running in my context that consumes the cpu.
• Then I clicked on "Show processes from all users" and found WinSAT.exe that consumes the cpu, it was running in System context.
  
• Now I started process explorer to get the binary executable path. WinSAT.exe is located in the system32 folder - it is a M$ binary. Using process explorers task details gives the description "Windows System Assessment Tool".
• Now I was sure that I can kill the task and I killed it. After killing the task the basic theme changed back to aero theme.
  

What is WinSAT.exe good for?

WinSAT.exe is used for generating the Windows Experience Index. By default the WEI is generated each Sunday at 1:00am or manually thru basic computer information window.

How to disable automatic scheduling of WinSAT.exe?

Start task scheduler management console taskschd.msc. On the left pane navigate to "Task Scheduler Library\Microsoft\Windows\Maintenance". On the right pane select WinSAT, click right and select "Disable".