Ready to try a virtual field trip or videoconference, but don't have a Polycom? One district in Vermont does both using just a web cam. Below is some information they provided - both about the type of equipment you would need and how to actually make the connections - that will help you get started: 

Equipment You Will Need:

• Laptop
• LCD projector for projecting laptop screen to classroom
• USB Webcam (with long cable preferably so it can be positioned with view of class)
• We are using the Microsoft LifeCam Studio™ Webcam.  It has a tripod mount.  It costs $85 or so.  It has a reasonable length usb cord (6') and we are experimenting with USB extension cables.
• Microphone (with long cable or cable extender is helpful for getting to students during conference for questions)
• We are using the Gigaware® Omni-Directional Clip-On PC Microphone from RadioShack, for $15.  It can be set in the middle of a large table and will pick up sound well.  It also has an on-off button which is convenient when you want to mute your site to avoid extraneous noise.  It comes with a 6' cable.  You can get a standard AV extension cable for it.
• Speakers
• Any good bookshelf speakers will do.  We are using either the Cyber Acoustics CA 2100wb (~$25) or Cyber Acoustics CA 3001 if you want a 3-piece system.  It is important to separate the speakers and the microphone to avoid feedback across the Scopia network.  This sounds like gongs echoing. 

Technical Considerations:

• Network cord to hard-wire connection - unless you have really good wireless access, a hard-wired ethernet connection is preferable.  This is particularly true for video field trips.  If you are just video-conferencing with a few other people you may not mind a poorer quality video signal.

• Audio - Audio is the most important signal to do well.  The most common problem is relying on the speaker and microphone in the laptop.  These frequently create echoing feedback.  If you are the only person in the conference a headset will work.  However, the clip-on PC mike can keep the separation between speaker and microphone far enough to avoid this problem.  In addition, if there are multiple groups conferencing, mute your mike unless you need to contribute to the discussion.

• Proxy Bypass - If you are going through a proxy filter, there may likely be problems with the signal.  We suggest setting the laptop up with a static IP that does not go through the filter when you are video conferencing.  You will need to talk to your network managers and test your connection with a remote site to determine what needs to be set up for use in your school/district.