for windows, go with winmedia (we are using it over 2 years - pretty like it), or you could go with Emuilve (www.emulive.com
), but it costs $$$
for linux try ffserver.
hardware depends on resolutions, framerate, codecs, etc... just use BT878 chip videograbber cards.
and one more suggest - you probably will spend lots (A LOT!) of time to get good quality of video (there are so many games with lighting, software/hardware settings, cams options, etc...). So suggest is: don't buy whole 10 cams, computers, servers, software at once. get one cam,production computer, server - setup it, be sure you could get the quality you need, then replicate this setup.