Best Software for Media Server + Step by Step instructions

Hi everyone!

I have a computer all ready to go with a few large hard drives. I have a ton of media between music and movies and would love to serve it up to my whole house. I've got a mix of Mac, PC (home built and store bought) and even TiVo. My question is:

1) Which operating system do you guys recommend that would allow my various systems to play nicely with? I know this is probably complicated, but I guess even more so if there is no "good" answer to this, which would most easily be accessible so I could at least move stuff on and off the server as needed?

2) As a guy who is pretty technical and knows some basic programming and computers in general, but doesn't know a ton about networks and network OS's, can you recommend fairly followable directions on how to set up the software once it is installed? Seems like there is alot of good linux distros out there that might do this, but I am open to anything.

I tried Windows Home Server Beta a while back but got frustrated with a whole evening of trying to get it to work in general.

Thanks as always!