I also think your question is wider than you first suggested, and it could
easily drift off topic into the realms of troll'dom.
This is my take: Technology is adequate if it does what it says on the tin.
But you usually need to right tin opener to use it.
Both linux based, and MS based solutions are better if placed in the right
hands. The trick is to look at available skills. if you only have skills in
asp.net and windows based servers then stick with that and work a solution
around it, and same for Linux/PHP. If your worried about cost, compare the
cost of replacing the skills of your existing staff, or recruiting new ones
to the cost of choosing a technology because you think its the best. Its
not a balanced approach to architecting a solution. In any media solution,
technology choice is way down the list of worries - performance and managing
bandwidth are usually paramount to success, and choosing the incorrect media
type to stream can cripple the most well meaning and best architected
venture.
Let your technology choice be the result of your requirements, and then let
skills dictate your eventual choice. You may still end up with the open
source model if its more appropriate and licence cost becomes a critical
factor.....but don't forget - Open Source does not always mean free.
Start by reading upon what to consider in a streaming solution to help you
plan some formal requirements, and determine a high level design to help you
choose an appropriate technical solution.
This will get you started.
http://www.networkworld.com/techinsider/2002/0114stream/index.html
Regards
John Timney (MVP)