I've decided to build a media server so that 2 laptops, one PC and about 3 TV's can all enjoy On-Demand media from one server.

Few questions, Minimum specs? At the moment (just lying around the house), i have an intel E6600 (and motherboard), Faulty RAM (so ill need to get some more, what is a good amount for a media server? 2GB? or will i need 4GB? is RAM speed important in a server?). I also have a 550W PSU.

Operating Systems: I was originally just planning on running Windows 7 on it, but have since been looking into Windows Home Server and Windows Server 2008. Recommendations? and advantages of a Server operating system?

Last question :) What type of network will i need? Will i get by with a Wireless N? (the entire network will be wireless apart from the one PC which wont be using media streaming). So the network will have about 3-4 devices streaming AVI's from the server. Any recommendations?

I know its alot of info/question, but any advice is very much appreciated.