How to set up a home network [Question, not Guide]

Well, recently I've stumbled onto an idea I find could be worthwhile for me.

I have multiple pc's in my house, all used for different reasons. One's a gaming PC, one's for music, I have one running linux, and just a random laptop.

I was wondering, how would I go about setting up a home network, where each computer could access the other one so I could listen to music on say, my gaming PC, instead of going to my music PC, instead of putting them all into one, then maybe access my music PC with my laptop. Is there any guide out there I could use to this?

I have wireless on all of my computers, with a router hooked up to the bottom PC [I don't want to access files on the bottom PC, that can not be included].

I have Windows XP professional on all my PC's except the one running Linux. Anybody have any suggestions for some less experienced [not using the biggest terms?]

Well, I just don't want to deal with iTunes as a software. I'd rather be dealing with the hardware side of things, just to get experience, and I'll know what to do.

Yes, this computer would always be on in my room, well, for the most part when I need it. I was thinking maybe getting an eSATA drive, hooking it up to my computer, and setting up the drive on the network. Would this be a smart idea or not? [I'll be running wireless!]

Another question, how exactly would you go about sharing a drive? I think I have an idea - right click on drive and click the button that says share. WOuld this be the correct, and most safe way?

Your best bet is putting to use an obsolete comp as a dedicated file server, but put a hefty HDD into it.
Otherwise look into a NAS unit, but deal with slow transfer rates as it converts files to/and from a conformant form.