I have an Acer V5-431 notebook
I had to replace the hard drive (for other reasons), afterwards I installed Windows 7 and i noticed the mouse wasn't moving, I had to plug a mouse into it
I'm sure the mousepad is connected to the motherboard correctly, I didn't knock it or anything and the touchpad driver is installed, it just wont work and I have to use a mouse plugged into it,
I have a stupid question, but I have to ask, did you try the <Fn> + <F7> function for the touchpad.
When you connect the cable for the touchpad, you are sure you press the connector latch until it locks into place.