This might help:
Especially for me, on that computer (now deceased... my kid unplugged it and somehow corrupted the BIOS on it. Yes, folks, the Dell Inspiron N-7110 is no more.) I put:
"Option" "FingerLow" "30"
"Option" "FingerHigh" "30"
Basically, what's happening is that the touchpad has a tiny area where your finger touches, and you have to move outside that area for the touchpad to register movement... if that area is too small, even a tiny twitch of your finger will register as movement, and you'll see your cursor jumping around with the tiniest finger movement, or the cursor jumping when you lift your finger off the touchpad... making the area larger makes the touchpad less sensitive.