Back up just SOME of the music library to an external hard drive

Question

I want to move just some of my music from my iTunes library onto an external hard drive (reason? the music cannot be got again, but right now I am not sure if I need it all or not).
So I want to move, say, 50 albums from the main iTunes libraray to an external drive and then be able to move some or all of them back again at later date.
Do I have to copy the whole library over to the external drive and then delete the albums there that I did not want to copy over?  Or is there a better way?
And how will I copy back just some of the back-up albums at a later date - is it the normal "Add folder/file to [main] library command from the File menu?

Answer 1

OK, I don't think I have been making it very clear what I am trying to achieve - let me try putting it differently!!
I have one iTunes folder and, at the moment, that is all backed-up via SyncToy.  I only have music in iTunes.
Think of that music as being of 2 types - part A that I want for definite, and all that music is also on my iPod (I have my iPod set to Sync manually with iTunes) - this is probably well over 100 albums; and Part B music, that is on iTunes, not on the Ipod, and that I am not sure yet if I want to have in iTunes and on the iPod or not (this was a load of music copied over from another iPod several months ago) - this might be a further 50 albums.
So - part A, I want to keep and want to be fully backed-up.  OK, SyncToy does that currently by backing up 100% of iTunes.
But part B - I want to copy the part B music to a different copy location, and then just keep there the part B stuff which, album by album, I will either delete completely (if I don't want it) OR want to copy back to iTunes.  Once this second copy is set up, I would delete from this copy all the Part A stuff, and also delete from iTunes all the part B stuff.
I would then have:
- part A stuff on iTunes, iPod and back-up location 1;
- part B stuff on back-up location 2.
So the main question is - from what level in the iTunes folder do I need to copy over to the part B back-up so as to ensure that, when I subsequently try to copy albums back from the part B back-up to iTunes, I get all the information, artwork etc that already exists for the albums?  Do I copy the music file; the media file, or the whole iTunes folder?
This may sound all terribly longwinded but, for various reasons, I am not in a position to be able to decide all at once which of the part B albums I need to keep.
Is that any clearer?
Cheers!