I'm dual-booting Ubuntu 12.04 and Windows 7. The only thing I still do in Windows is use Double Image to backup my data from my D-Link DNS 321 NAS to a local hard drive. Once I learn how to do such a backup in Ubuntu, I'll probably not use Windows anymore.

Here is one requirement for the backup: Backed up files are as the original files (not in a backup format)

In Ubuntu Places, I can see and access my NAS, but from inside Linux backup programs such as Duplicity and BackinTime, my NAS is not visible.

My question: is there a way in Linux, using software and little if any command line programming, to backup data from my NAS to a local hard drive? If so, could you please inform me? Thank you.

there is a program called bacula, which is a backup manager, not sure if it's command line or gui but webmin http://webmin.com/ can manage bacula nicely.

other than that, most of the software is command line, not that you always have to type the command, you can learn enough just long enough to write a quick script and run that with cron.

A few hundred ways to backup maybe. Each has some issues good and bad.

General ways. You shouldn't need any sort of file by file copy. Almost any backup plan can dig into some compressed format and retrieve a file.
Backup to a single compressed file. Modern linux can usually dig into the file and get single or groups of files back.
Clone image of disk or partitions. Again linux can mount those images.
Backup only files that you select by schema on.
Could go wild with an isci target deal and rsync it all.

From ubuntu pages. https://help.ubuntu.com/community/BackupYourSystem

Forgot clonezilla and commercial tools like Acronis.

As to why NAS isn't "found", you'd have to explain more. How does linux find it?

and why do those programs not see your NAS? is it not mounted? If it is mounted properly then those programs will detect it as just an other storage location. Worse case enable FTP on your NAS and im sure at least one of those programs can push the data either via FTP or rsync.

Why so afraid of the command line? if you really want to do something or learn something in linux use the command line.

Depending on what you want to backup you could write a simple BASH script containing a few dozen lines and be done with it.

Many file browsers have a SMB/CIFS (the windows file and printer sharing protocol) client built in so it isn't necessary to mount the file system. This is why the backup programs do not "see" the NAS.

As stated you should mount the NAS like:

mount -t cifs /NAS_IP_address/share_name /media/NAS

You will need to create a directory first to use as a mount point.

and that was what i was trying to get the OP to understand. if the NAS is not mounted, NO software will see it unless told to mount it.

the OP could place a fstab entry or make an autofs file or what ever the replacement for autofs is called, or the OP can just manually learn how to use the CLI and mount the drive properly.