I use Norton Ghost regularly as i dont like the Windows System Restore and find it is a lot more reliable. But I cant say i have ever tried to Ghost an image to a larger drive! Nowhere in the Ghost help does it say you cant do it tho! At worst, the way I see it, it would copy the 80g to the 200g as an 80g partition (maybe) then I presume you can just allocate the free space (the remainding 120g) or create other Partitions then merge them together.
What will work for you is making a backup (or ghost image) of your 80g drive and copy it directly to dvd's. This will take a few hours tho and a few dvd's, expecially if you only have the one drive as Ghost can not save the image to the drive you are ghosting.
I have 2 harddrives, when I ghost one drive I copy to the other. Then I copy the created ghost images to dvd's. When I want to restore the ghost image of my C: I just copy the Image from the dvd's back to my d: then ghost it to my C:. I sounds like a lot of work but it really isnt and you get a nice clean fresh install again of windows. And doing it this way the whole process takes approx 20 minutes!
Do you have a spare smaller drive? That way you can backup your 80gig then say using a 10gig have a go a ghosting the 10gig to the 80gig. If it works then you know you are safe to do the 80 to the 200.
But I also think it will work.