With the interactive whiteboards you are very limited in the size of the image and it is usually smaller than normal. Therefore most projectors are going to have to be mounted closer to the screen than normal. At 14 feet the old projector probably (not sure?) had a special lens in order to allow it to fit onto the whiteboard. You need to use the distance calculater that is located on the main page.http://www.projectorcentral.com/projection-calculator-pro.cfm
The size of the image is very relevant to the distance from the screen.
There are definately some projectors out there that can meet your needs that will not need to be mounted onto the ceiling but they will probably be slightly more expensive.