Hi Elenkovan,
You shouldn't need to backup the VSP files. There're probably there because it wasn't cleanup gracefully.
Try add the VSP file in the backup exclude list and if everything is alright, remove the vsp files (you may need to reboot the backup client to release the file lock prior deleting or you can consider some of the utilities recommended in this forum to remove file lock without reboot the client)
Having said the above, I wondering whether NBU4.5 supports Win2k3 client. Let me check the compatibility list.......