I think you may have to do them individually I'm afraid. If you hadn't synced it yet, it would have been possible to sort it out, but unfortunately, you're out of luck.

Treat it as an opportunity to spring clean your pod as well!

but if you have zero tracks selected (and you're on a PC)

a) fire up itunes
b) select 'music' at the left hand side
c) list appears in big pane of all your music, and should be tickless, right?
d) select one track - it'll be highlighted in blue
e) Ctrl A
f) they're all blue now, aren't they?
g) right click on this blue mass
h) click 'Check selection'
i) they're all ticked.

If this isn't what you wanted, sorry for wasting your time!

You can also select ranges of tracks but clicking on one track, holding down the shift key and then clicking on another track. This will also select everything between those two tracks.

I don't believe you can select contiguously in iTunes yet though.

I signed up to this, in a fit of madness, so now I can access all my music from my iPhone, wherever I am. But there's more music available than my iPhone can hold, so presumably, if I choose to play any of that music, I'm downloading it, and eating in to my monthly download allowance. Or am I wrong?

Ah. My apologies.

I assumed that you (like me) don't have everything that's on your iTunes on your iPod.

Holding Control down when clicking a tickbox will tick all the items in the view.

it's a spectacularly rubbish piece of software.

The fact that it default to loading everything on the host (unlikely in most cases) and wipes your iPod, iPhone or whatever, is poor.

If you save files in a playlist, then that might give you an easier route to reconstituting a previously downloaded dataset.

The synchronisation should be streamlined to a single screen for all media (rather than separate faux tabs), and the whole clunky user interface should have been redesigned by now.