Leonard

If I was doing this for myself or one of my friend I would be recommending that the drive in the old system be replaced and selling the system with the new drive installed. Drives are relatively cheap now. This would be a positive in the purchase for the buyer as they are not getting a seven year old hard drive.

I would be keeping the old drive.

That way you are also keeping your data away from prying eyes and will still retain all of the connections to your synced data if all else fails.

In my experience drives should not really be depended on for much longer than the warranty.

Alan Smedley