estimate max connections to live stream on FMS 4.5.2

We are planning a large scale streaming event in the future and are trying to estimate the maximum number of user connections that our FMS 4.5.2 Interactive Server can handle.

The server is Windows Server 2008 R2 Standard, 4GB RAM, 64-Bit OS and has 1Gbps bandwidth available. For simplicity if we encode a single stream at 500Kbps, what would the estimated maximum number of client connections that the server would be handle?

Thanks,

Dave