Hi Jen
The Science dept was one of the first to get Interactive Whiteboards in the school 4-5 years ago (this is my 3rd year). They got a full system where not only could the computer in the lab (and therefore the web) be put through the whiteboard, but videos could be put in video machines in the library and "piped" to the specific whiteboard when wanted. Science staff have developed resources to put lessons through the computer onto the whiteboard and you can save any "written" work from the board (brainstorming) back onto the computer. They say that board has helped streamline their teaching to get more done, include more resources and present them in an interesting way.
Some points to consider :- there are now other products that turn an ordinary whiteboard into an interactive one far cheaper than this system.
-we have had trouble with the "components" in the whiteboards which have been
extremely annoying for the teachers (the writing runs off/ slopes at the edges/ can't touch exactly where you were before) so that some of them have been replaced (no charge!) Definitely need a backup whiteboard in the room (preferably on the wall).
- there is a thought among some teachers that it cements the "teacher centric" way of teaching and that they should not be called "interactive" as they don't promote this style of teaching

Just some thoughts, and not necessarily my own! Hope it helps. Sue G