Linux-based network fileserver for media streaming

[BasharOfTheAges]

So, I'm upgrading my home network in several stages over the next 6 months... Installing a 2nd line (25/1 DSL) to complement the 12/4 Cable line with a load-balancing oracle router, running redundant CAT6a wired connections to every room, setting up a decently beefy switch to route all the internal traffic to up to everything, and building a ~10TB networked media storage device. The networking stuff is all pretty straight forward, but I'm looking for options with the media server. I'd like for it to run some flavor of linux so I don't need to go out and get another windows license, but it needs to play well with multiple Win7 installs, at least 1 mac, several different video game systems, and maybe even some of those small WD LIVE boxes that play everything. I'm dropping my old C2D system (with 8GB of DDR2) into a case and building up a huge RAID array (through a PCI card I think) of SATAII 2TB drives. What are my best options for complete compatibility though? Should I use something like mediatomb (UPnP) or is there any real reason to have it set up anything more than a simple remote filesystem (formatted as what?). I'm sure there's going to be some pitfalls that i'm not seeing yet, so what are they?

[BasharOfTheAges]

Forgot to add (and would have through edit if my donation had gone through correctly) that I might want this thing to also work as a seedbox.

Also, the 24/7 nature of it's uptime makes me also want to ask about the need for cooling.