The D partition is from the manufacture and is NOT intended for your use! it is used only when or if you would need to recover the system to the day-1 state as you received your system.1)vista sp2
2)just the weekly backup of persnal files & folders (pics/docs)
3)the computer came partioned w/"d" drive as "recovery"/backup
4)on partion of single harddrive as noted above (8 gig)
5)scheduled once weekly after hours of use "the last backup failed"