Backing up multiple source drives to multiple destination drives please help

My PC has two internal HDDs, one 500 gb (C), one 1tb (T).  I ran two backups the other day separately, one for C and one for T.  But they didn't fit on my external 1tb drive even with high compression.  So I am thinking about buying a new external hdd.  And running two backups, one for C on the first externall HDD and one for T on the newly purchased external HDD.  Does this make sense and does it work with Norton Ghost?  Anyone encountered any problems doing this?

 

Or can anyone think of a way to get my C and T drives to fit on one external HDD??

 

Thanks in advance.