Okay, this takes some explaining, be patient with me.

pre-2005: I had a ton of mp3's on my desktop computer.
2005: I got a laptop and iTunes.

I was going on a long trip and was in a hurry, so I just transferred 50% or so of my music onto my laptop and imported it into iTunes. Took me ages to get all the names fixed (in 99% of cases, the title and artist were swapped).

Fast forward to now, and somehow, I never really got around to adding the rest of that music from my desktop into my laptop and iTunes. Plus, I've added lots of new music into my laptop now.

I don't use my desktop much anymore, so I miss the music that's on it. Plus, having two separate-but-kinda-overlapping music collections is annoying.

So the question is, what's the most painless way to merge my two collections of music when copying my desktop music over to my laptop. What I really want to avoid is having duplicates of anything. Unfortunately, since my old music looks like "Norah Jones -- Nightingale" and iTunes has it as "Nightingale -- Norah Jones," it may be unavoidable, since I don't think the program will recognize them as the same thing.