Backing Up (but a bit diff to the norm)

I know there is tons on backing up here and i have had a quick nose but can't find the answer i need.

So I have a dual boot win7 64 bit machine (and D is used 99% of the time, C only there as a back up in case D goes down) I use an app called Arkbackup to back up my normal files on a daily basis, these being my docs/my pics/emails/newsleecher/winrar/digiguide and other apps folders that are needed, these are then backed up to drive I as i say on a daily basis.

Now what i want to do is take a complete back up off ALL necciserisy files and folders for iTunes this will also include, not only files to allow full restore if drive crashes but also all the musis files themselves (so about 70GB in total) these will be then stored on and External USB 2TB drive, then i will set Arkbackup to back up everyday all iTunes files/folders EXCEPT the music files, of course i will back up Automatically Add to iTunes/.iTunes Preferences/iPod Games/Movies everyday but what other files and folders do i need to back up bearing in mind D is my OS drive here.

In a nut shell playlist/times played etc etc needs to be kept so i can restore if it all goes bad and needed to be installed on a new machine, one last thing does it matter if new machine had different user name, for example my PC is called All1 if i have another machine named Laptop will i be able to install on there?

All1