First, is your SSID visible or hidden. When you bring a new wirelss workstation or laptop on your network, does it automatically disply your wirless router name? If it is set to do this, your SSID is visible. Are you finding any other wireless network with the printer? Sometimes if you live in a subdivison or apartment complex someone has a wireless device and even though it may be secured your device should still see it.
Have you followed these directions
http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&dlc=&cc=us&product=1153494&docname=c00724861
