Norton 360 - will not back up to my external HD

Norton Security | Norton Internet Security
1

I have a 465 Gb external hard drive that I use only for my Norton 360 back up.  It will not back up because it says that it is now full.

 

Why doesn't the back up over-write over an earlier back up?

 

Is there something I can do with settings?

 

Can I just delete what ever is on the HD and do a back-up?

2

I have Windows XP.  How do I tell which version of Norton 360 I currently have?

 

The back ups are located in folders on my external hard drive.

3

I have a 465 Gb external hard drive that I use only for my Norton 360 back up.  It will not back up because it says that it is now full.

 

Why doesn't the back up over-write over an earlier back up?

 

Is there something I can do with settings?

 

Can I just delete what ever is on the HD and do a back-up?