Centralized Mutli-platform Music Library

So I've recently come upon enough time to actually focus on this and I'm just really coming up empty. I currently have most of my music split between a 320g hdd and my laptop. This was fine as both are portable and when I wanted music from the hdd, I would just move it to the laptop into the iTunes library. Laptop runs OSX and Win7. I also run a Win7 desktop that is now my "main" computer. I am doing a lot of my music searching/downloading on this "main" computer.

So the problem is, does anyone have a centralized music library that they are able to access without issue from multiple platforms?
In this scenario I would like to
-avoid any "cloud" bullshit.
-continue to use iTunes or something equally as polished (it just works, art work is a must and iTunes makes this super easy)
-FREE (Unless this solution shits rainbows, I'm not going to pay for it)


My 1st thought, iTunes using a networked drive.
Problems: I'd have to always have a network connection to access music, no localized music

2. iTunes using mirrored network drives... IE: Sync from centralized directory so that the library would be localized on each of the needed machines. Maintaining "identical" separate libraries and telling the synced computer of the iTunes to search directory for updates.

3. Find a program as easy to use/update as iTunes but will also be able to sync libraries internally without any "hacking".

4. Although not a requirement, I'd like to be able to sync with multiple devices. This is easy enough to get around but I don't use an iPod/iPhone as my main music device but I do have an old iPod that I keep in the car for long trips. I would need to be able to sync to multiple devices.

Bottom line: Anyone implemented or tried something along these lines? Results?