I'd use the router as a network boundary to filter out broadcast traffic and serve as the single point of entry for Internet traffic for downloading software updates. The hub could be used to make a star network topology so that the workstations can communicate with one another for file sharing and software publishing purposes.
Since most workstations come with a 10/100 Ethernet adapter installed already, this would give the network 100 Mbps speed on the cheap since 100BASE-T cabling is easy to install and work with giving you good wired LAN speeds for a small office. If the office isn't more than 100 meters in any direction, you shouldn't have to purchase any other hubs or repeaters to connect all workstations and servers - this will save you from having to put in patch panels to connect further segments.
Your server will need to have two NICs so that you can connect it to the Router at the network boundary for accessing the Internet outside and connect to the hub on the internal network.
On some routers, there is a method by which you can set / limit the hours during which the machines can connect to the Internet, i'd look into setting up those hours to occur during business hours only. Maybe give yourself an additional hour before or after business hours for downloading software updates.
Remember that with your cable lengths and runs, you need to factor in about 10-12 additional feet (at each end of the cable) if you are going to run the cabling up to the ceiling, across the ceiling panels, and then back down to the ground again to avoid having the cables on the floor. Many people will forget to do this when looking at a cable plan from bird's eye view and find that their cable length estimates fall short by about 20-24 feet.
Edited by Cyb3r_Ninj@, 13 December 2007 - 12:53 PM.