Drivers - will be in the windows system folders so only a backup is required/ preferable in a separate partition.
Applications - I never (if possible) allow applications to in stall to the default c:\program files\??? I always put on a separate partition.
This allows me to keep the C: partition small and therefore makes it quick and easy to make a back up / restore an image of this partition. If windows fails I can restore the image and be working again in less than 10 minutes.