In this case a server needs to provide:
- file server for approximately 10 people. This is for shared files only, not storage for network based workstations.
- apache server with php for admin panel
- apache, php and mysql for a lightly used application
This would be an appliance, so no need for sound or high end video capabilities.
You need to examine your needs from the point of network & hdd bandwidth.
How many files and how much bandwidth will they need at any one time worste case scenario if you will. This will determine what you need server-wise.