Aero Theme is bad for your computer’s resource usage, if you haven’t gotten that insight yourself already.
Disabling the Aero theme is easy, however Microsoft went through some hoops to make you look for the option. Once you know where it is it’s easy.Right-click an empty spot on your desktop and click Personalize. Click on the Window Color and Appearance link. Click on the “Open classic appearance properties for more color options” link.

BTW, you can also run the following command from the Run option in the Start menu:

“C:\Windows\system32\rundll32.exe” Shell32.dll,Control_RunDLL desk.cpl,Appearance,@Appearance