Hyd, I'm in the same position too. I copied every last file I could find to do with Sonicstage/Sony, including stuff in Common Files, All Users, even the WinNT System32 folder. It restored all my packages, but said the songs had become corrupted.
I've resorted to having to recopy all my CD's back again. At least the situation isn't unsolvable, with a spare day and a very hot CD drive. Unfortunately, the result is that I haven't got round to it yet and am just not using my MD any more.
Surely Sony could show how to back up your own copied CD's for those of us with the technical know-how to do it without resorting to the unusable (especially if you're talking in the quantities of CD's we are) Backup app?
Or I guess, if you want to seriously use the NetMD, you're just NEVER allowed to change your operating system or computer. Good policy, Sony.
Ben