Networking and Server setup

I wasn't sure what the best area was to post this so I thought I would put it here:

Currently we are running a Video Production company and photography business from one studio. We have 3 macs in a row. One is used for Video, the other two for photography. The video production is edited in Final Cut and we also do other compositing. The photography is heavily reliant on using Aperture to store all images, and then photoshop for post work.

My question is: we are currently just working of hard drives connected to the computers. What we want is a server that allows us to all access the same files and documents from a central area that stores all the data. We would like separate locations for video and photography and for this to be accessible quickly, especially considering the video we shoot is HD so transfer rate is important. We also want to know that at the end of the day, all the work that has been done that day is backed up, in case something goes wrong.

Can anyway give us some detailed info on what the best set up is for us in this situation?

Thanks