I've installed OCS 2007 Communicator R2. When I join a multi-party audio conference, my dual core laptop has 50% of both cores utilized at all times. If I launch a web browser or open an email, the cores go to 100%. I get complete jitter. OCS tries to catch up the audio but many times it falls too far behind. Since other users in my company aren't experiencing this on Vista or Win 2008, one thought is that this is due to the network card drivers. I ran Communicator 2007 RTM on Win7 with no issues. I did an internet bandwidth test to the OCS servers' location and get 15 Mbps down and 5 Mbps up with Comcast. I tried this at Starbucks with same issues. I reinstalled communicator and have only used it twice. One time it was still bad (30% utilization of both cores), but not as bad. I'm also wondering if the number of people on the conference is directly proportional to the core utilization. The first call I'm talking about had 9 people on the audio conference. The last 2 only had 2 people each time.