Connecting My Network to Broadband

I provide (amateur) support for a small network at my church. Single NT4 Server, Workstations: 6 NT4, 1 Win2k, 2 Win98SE. One of the Win98’s runs my backup jobs. One HP8000N workgroup printer and one of those Color copiers with Net interface for printing. All connected up with 100MB ethernet (switch).

I need to connect a broadband internet solution, probably AT&T Broadband, providing connectivity to all stations. Anyone care to sketch a basic approach, at a minimum touching on:
– Connectivity (hardware)
– Firewall (software/hardware?)
– Content Filtering

Thanks.