[geeky] Odd stuff I’ve learned setting up a new Mac

I've been in the process of setting up a new computer and in the process, as is expected, discovering long lost files and stuff that is easier or harder to move over. I thought I would capture some of the tidbits because there might be something useful here for you

To set the scene, this is a new Mac Pro (the tower, Intel, 64bit, running Snow Leopard) replacing an old Power Mac (the old tower, PowerPC, 32bit, running Leopard.) You can stop now if you're a PC. To the untrained eye, these computers are exactly the same inside and out. But wait.
Based on past experiences (with all computers) I decided not to let the automated process 'move over' the stuff from the Old to the New computer. Instead, this is a good moment to get rid of all the dreck that has accumulated over the years and start with a clean slate. Good choice.
Moving over my considerable size iTunes library ran into snags. Not moving it, that was easy, but discovering a bunch of music that didn't play anymore.
The new iTunes 9 has a very nice new feature (called Home Share) which solves the problem of having several computers in the house and several iPods, and constantly having to move songs from one to the other etc. Instead you can have iTunes publish the whole library in a way that other computers at home can see, and in addition (and this is the new part) import onto the other computer. So I simply Home Shared the library on the Old computer, and then went to the new one, and imported the whole thing. Very nice.
But some songs said, "This computer is not Authorized." Etc. What I discovered was that you can go to a song like that, on the old computer, and look at the info box, where it will show what old email account you had used when you first ripped that song from your CD, and then simply go to the new computer and "Authorize" it on that email address.
Which works just fine, as long as those email addresses all correspond to various iTunes Store accounts you've had over the years. I had 4 and I remembered all their passwords, and all was good. So here's a headline: it is perfectly possible to Authorize one iTunes install with multiple iTunes account. Any particular iTunes account can only be Authorized with 5 iTunes installs though. Very confusing, the world of DRM!
But, I discovered a handful of songs in my iTunes library that were associated with an email address that I never used in iTunes. So when I try to play one of those, they say, this computer is not Authorized, please Authorize it. And then when you try to Authorize it, it asks iTunes Store, who says "Never heard of this guy", and essentially the effect is that those songs cannot be played.
Cannot be played, even though they were copied from physical CDs that you own!
My theory is that I ripped those particular CDs, by mistake, with AAC encoding, which is Apple's DRM encoding. But for some mysterious reason the resulting files are associated with a nonsense email (don't know where they came from) and therefore they cannot be read!
The Apple "Specialist/Expert" was totally useless in solving this problem. I am now trying to prove that this is somehow the result of the new iTunes.

Hope that some tidbit in that is a little useful to someone. I now it's ridiculously arcane but I just had to share my voyage of discovery with you 🙂