What is your budget?
This question will immediately narrow down your choices of venders as well as options. A smaller budget might be limited to webcams and headsets, while a larger budget would include a higher end camera and audio system.
How do you plan to use videoconferencing? (person to person, person to many people, many people to many people)
This will influence your decision and can mean the difference between spending a hundred dollars or a few thousand dollars. A person to person conference over the internet can be done using a webcam and microphone over existing software that is freely available like iChat, or MSN Messenger. A person to many conference may require more expensive equipment to help everyone in the room access the content in the same way.
Will you need to use video and data conferencing to share your computer screen with the end users or do other types of collaboration?
Are you planning to do PD events or videoconferences that require staff and students to share their computer screens for presentations or collaborations with the remote site. If so, then the equipment that you choose needs to support this feature.
How will you ensure a quality audio/video connection?
You may need to investigate network software/hardware that will help ensure that bandwidth on the network will be dedicated to the videoconferences when they occur, this could mean QoS (Quality of Service) software or a hardware bridge to boost signal throughput. Something to remember: you may have large bandwidth and great connections within your board intranet, but when you are going out over the internet all bets are off.
What type of connections will you need to support?
The remote sites that you plan to connect will support certain videoconference protocols or methods. There is a move to standardize connections but it is still a bit of the Wild West. Make sure that the equipment that you purchase will support the widest standards possible including the H 323 and all its variants, as well as newer standards like SIP. Make sure that the software on the videoconference unit is easily upgradeable and that you do not need to make another hardware purchase just to keep up with videoconference standards.
If the remote site only supports ISDN (most donÃ¢â‚¬â„¢t), then you need to ensure that your equipment supports ISDN as well as IP based connections.
What kind of warranties and support will you get from the vendor?
Check if the vendor will continue to update new standards on your equipment without charging you to do it and for how long will the support last. Make sure that the videoconference unit works well with other vendors. If you are planning to do videoconferences with remote sites you need to feel assured that your equipment will work with other vendors equipment.
The Videoconference Cookbook is another great resource if you would like to learn more about videoconferencing. It gets into more details.