Backing up Two external WD MyBooks

I originally had a PC and one WDMyBook for backup - and all was working fine.  I had to add another WDMyBook external drive to create capacity - and moved all of my iTunes files to that external drive.  I am now trying to back up my PC and the files on the external media drive to the external backup drive - but when I go into the WD SmartWare I am not seeing an option to select / configure the backup to include the external media drive in the backup?  I am operating the backup in “category” mode.  Running a PC, Windows VISTA-64

Smartware only supports internal drive or another non smartware external drive…

Thanks.  The folks at WD Support said that I could flip into file backup mode and the drive would appear - and that is not the case - only the nonWD drive appeared.  It appears that you know more about their product than they do!  Can you recommend any good backup software that I can use to run my backups?