I like these two HD webcam's
Logitech HD Pro Webcam C910
&
Microsoft HD LifeCam Cinema
Both sell for about $100 The Microsoft camera is the less expensive. One thing to consider is bandwidth, do you have the bandwidth to upload streaming HD? It is significantly more data. I would suggest keeping your old camera handy even if you do as it is possible that some of the people that you interact with may not have enough bandwidth to download the HD (this is a worse experience than the low-res images).
Another issue with HD is play with the lighting and consider make-up, HD can really bring out any minor flaws (for example occassionally video conferenced with a lady for several years, her office migrated to VOIP & HD, she had some facial hair that was very visible in the HD that no one could see with the old equipment. Apparently, someone(s) were obnoxious about the hair and she left the company). I would make sure that you are comfortable with the HD before implementing.
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