If you wish to set up natural scrolling for Ubuntu (11.04 and 11.10 ), you may download and install it from the OS's own PPA. What you should do is include ‘ppa:zedtux/naturalscrolling‘ to your Software Sources. Afterward, select "Update", and finally, you should install the ‘naturalscrolling’ package from the Ubuntu Software Centre. You may launch the applet by making use of Dash, and you may turn on natural scrolling through the Application Indicator that you may find in the top panel. Once you will have successfully activated natural scrolling, the program will display a small "tick" mark. If you wish to disable it, all you need to do is click again on the same source.
As far as Windows 7 is concerned, there are several prerequisites that you should tend to. First, you should make sure that you have installed AutoHotKey, an application that is peremptory for your desired result, and which you may download from this link: www.autohotkey.com/download/AutoHotkeyInstall.exe You also require a scroll-reversing script.
After AutoHotKey is installed, you should transfer your script to a safe directory. Afterward, double-click it. The script should then be functioning in the background, and you should be able to use natural scrolling.