Actually, the majority of my listening is via PC these days, mostly because I have more ability to do it at work than anywhere else (even when I'm busy), and yes - I'm obviously aware that I have to have the hard drive plugged in if I want to listen.
What I was getting at is that I don't actually use the library function in WMP at all (neither to play music, nor to keep track of it). I simply browse to my HDD using Windows Explorer, highlight the folder I want to play (since I mostly tend to listen to full albums at a time), and then right click and press play. If I want to make a playlist of multiple albums from a certain artist, I just repeat the steps above and add each album to the current playlist (which I obviously don't actually save).
What I'm really trying to find out, I guess, is how the mechanics of using iTunes all the time are going to change my listening and storage habits. I'm not really hip to the gory details of what info gets copied to where when files are "sync-ed" since, as I said, I'm used to playing directly from my HDD or adding / deleting files to and from a generic (read: Non-Apple) mp3 device using drag-and-drop.
It's not that I'm afraid I won't be able to figure out how to do it - I'm just looking for ideas on the most efficient way to get things done before I do a lot of experimenting with ideas that other folks have already tried and found to be crappy.
As the saying goes - a smart man learns from his mistakes, but a truly wise man learns from the other