make sure that you "Consolidate" the library.

In iTunes, File > Library > Organize Library and then Consolidate Library.

On completion, copy the entire iTunes folder to your other drive.

When you get your new computer;
PC: Install iTunes and then drag the saved library over to the new machine (best you do the save after every iTunes version change, in case the library format changes)
Mac: Use the Migration Assistant to move all your data from old to new. That would include the entire iTunes library and its settings

How's that?

P