is "Yes, you are correct." Though there is the proviso that Drive Image, (and I presume "Ghost" as well), can image directly to CD. If you use high compression the ratio is approx 1Gig data per CD. If you were to do this then you would not need to partition first... you could backup then partition.
2 Backup what you can't replace from Disc, or more specificaly, whatever you can't afford to loose! Only you can decide what that applies to. Now is perhaps a good time to be rid of all the clutter so go through all your data files and decide what can be "biffed" and you'll find that there is a lot less that you'll need to back up.
I hope this helps,