Resolder the speaker back to the wire. Screw and tape the speaker into position in the rightmost screw hole, facing down. The touchscreen controller will sit over the motherboard and the gap where the speaker had originally been.
Line the back of the controller with electrical tape to protect it from scuffs and prevent an (unlikely) short circuit. Position the controller board rotated slightly clockwise, with one corner well over the gap you created. The top corner should nestle closely to the bottom heat-sink screw and avoid screw holes on the motherboard. Also avoid the white dot above the original speaker position; the upper case rests here. (Sight with the upper case to see if it seems lined up properly.)
Tape the touchscreen controller in place. Reattach the Wi-Fi card, and run its wires back in the original path. Tape the touchscreen wires in place in the same channel or in the edge of the hard-drive cavity. (The hard drive will fit tighter if you do this, but there's just enough room.) Make sure you don't cover any screw holes.
Feel the Difference
Now it's time to put your baby back together. Reattach the LCD bezel and the plastic layer that contains the touchpad, connecting that ribbon cable and connecting the power-button cable near the top. Reattach the hard disk and RAM cover. Replace the screws along the way.
You did it! Windows 7 will automatically recognize the touchscreen, and you can calibrate it in the Control Panel. Your netbook might not look any different from the outside, but you've extended its life and given it an interface upgrade.