Video call with Audio/video problems.

A Lady friend and I have recently experienced problems during Video calls.
They are coming in with garbled audio & with choppy/ freezing videos. This
all started about 2 month ago. Prior to that we never had a problem. What is
causing this problem? Here are some quick facts. I'm using a desktop system
(Home XP with all patches) with a cable modem & router. She is using a 64 bit
Vista system on her wireless Gateway MD2614 laptop. I am guessing it is
related to Windows Live, or our internet connections. At least that is what
the support page for my webcam said (Logitech Pro 9000). From my end I can
usually hear her fine, but video is choppy. From her end, she tells me audio
is very garbled. It gotten so bad that we stopped doing Video calls.
So....HELP! What is causing this to happen? Is it Window Live? Is it a
resource hog program in background? Is it something else entirely? I would
appreciate any and all suggestions. Perhap via a process of elimination we
can resolve this nagging problem. If I left out some vital info, please let
me know. Thanks!
--
ULguy