For those that use a mouse a lot and are constantly switching between different Windows/Programs, the WizMouse application can be a big help. WizMouse enables scrolling in applications that are not active. Microsoft Windows by default does not allow scrolling unless the window/program is selected (active). WizMouse eliminates the need to first select the program and then scroll. WizMouse simply lets you mouse over a window/program to start scrolling. Once you start using this program you will wonder why you did not have this program before!
You can download this application at: http://antibody-software.com/web/software/software/wizmouse-makes-your-mouse-wheel-work-on-the-window-under-the-mouse/