xmodmap

In X (I'm using GNOME in particular) with num lock off, the numeric keypad doubles as direction keys, home, pgup, pgdn, and end keys. How do you disable this? In a plain terminal (outside of X) the numeric keypad does not do this.

I did some research and learned about xmodmap. I tried the following:

xmodmap -e "keycode 79 = KP_Home"
xmodmap -e "keycode 80 = KP_Up"
xmodmap -e "keycode 81 = KP_Page_Up"
xmodmap -e "keycode 83 = KP_Left"
xmodmap -e "keycode 84 = KP_Begin"
xmodmap -e "keycode 85 = KP_Right"
xmodmap -e "keycode 87 = KP_End"
xmodmap -e "keycode 88 = KP_Down"
xmodmap -e "keycode 89 = KP_Page_Down"
xmodmap -e "keycode 90 = KP_Insert"

But all that did was make the keypad with numlock on emulate the direction keys, home, etc. as well!

Thanks for your help.