I have already posted an entry somewhere on this blog on how to disable your touch pad if you plug in a usb mouse. But I've just found out that the arch wiki has a great summary on different kinds of touch pad settings including for a better palm detection:
synclient PalmMinWidth=4 PalmDetect=1
This works excellently for me - and I have a new system with a rather large touch pad. Enjoy! And as always: Please share your experience and ideas!