Ratings and playlists
How do I get my itunes ratings and playlists to my new computer? I switched the library files, but I may have done it in the wrong order.
HP
Make sure you copied the complete iTunes library - database & associated files, media folders, artwork, etc. - from the old computer to the new one. If you've configured iTunes to manage your library content everything should be within one iTunes folder - by default, C:\Users\username\Music\iTunes, with this structure:
See turingtest2's user tip on Make a split library portable for more details and steps you may need to go through to reorganize your library into this layout.
From your description it looks like you've done this, but iTunes could be picking up the wrong database (the iTunes Library.itl file) when it starts up. To check this, hold down the SHIFT key while you start iTunes; when you get this prompt:
click on Choose Library..., navigate to the folder containing the iTunes Library.itl file you copied from your old computer (which should be in the same structure as illustrated above) and click Open. This should restore your library to you, with playlists, ratings, etc. intact.
Note that doubling-clicking on an iTunes Library.itl file will start up iTunes but will not necessarily use that file as its database - unless you use the shift-start method it will always load the database file it was using the last time it was running.