Thank you for the link. It din't work, though. However I tried with the drivers for the touchpad for my HP model for Windows 8.... and it worked! Now the touchpad works perfectly with Windows 7.
Happy to be back to Windows 7! It's crazy to see the amount of energy Microsoft has invested in preventing us from unistalling Windows 8. They'd do better in investing all that huge energy in creating better Operative Systems. We'd all be better off.
Thank you for all your help.