Streaming Noob here.

I'm building a Windows 2008 R2 server to stream a couple Terabytes of movies on my LAN for about 400 users.

My Problems:
1. The movies are in various formats (avi, wmv, m4a)
2. I need a solution to minimize as much as possible network congestion
3. Also have concerns of overwhelming my server.

I've seen some stuff about streaming with VLC but I've never did it before.

Any ideas / advice as to how I can do this efficiently?