Help! Fix no video with quickcam behind MN-700 router

much appreciate if someone can help. i searched through old newsgroups but
cannot find a good answer.

i have a logitech quickcam orbit attached to my ASUS P5GDC-V motherboard
running windows xp sp2 and quickcam software 8.4.1 build 1092D. when i tried
video conference using windows messenger 4.7 or 5.1, the other side see
cannot see my video, though we can speak to each other (so audio is ok) and
i can see the other side's video. i believe this is a problem with my
firewall and router. i have turned off windows firewall and norton internet
security 2005 but problem still persists. i know the MN-700 router is uPnP.

1. can someone tell me how to check whether uPnP is turned on in my router?
2. what could be the problem and what is the fix?

please help.

btw, happy holidays to all.