Having read the answers in this discussion, I still would like to come up with the same question: What should I buy to run Flash Media Interactive Server 3.5? I just have slightly different boundary conditions. We plan to serve video to ca. 1,000 users simultaneously. It will be live stream, so the server will receive the stream in HD (1280x720), cache it, reformat to various other resolutions and send it to users. OS of choice is Linux, but if you say it should MS-DOS, so it will be...
What would be a decent server for this task?
What sort of network connection are you planning to have? the reason I ask is that we stream at around 6Mbps, a thousand unicast users at that speed is around 6Gbps - your server will keep up but will your switches/load-balancers/firewalls/routers?
As for a server, well for consistent 6Gbps of traffic (plus the ingress and transcoding work) you should really use a 'proper' server, i.e. not a desktop PC pretending to be a server, with at least 4 recent Xeon or Opteron cores, 6-12GB memory, a 64-bit OS, a pair of hardware-mirrored fairly standard boot/app disks and a pair of 10GB NICs (it's much harder to consistently feed multiple 1GB NICs). Then your choice of OS based on your available skills base.