Walter,

I'm sure you are wanting to go the most economical way possible.. but when
you are looking for devices with dual tape drives, and fairly large storage
capacity, that gets to be a challenge!  We have an ADIC Scalar 218 DLT
library.  We love it!!  The scalar library can store anywhere from 540 gb
to 1.26 tb.  They do have smaller libraries available.  For more
information, check http://www.adic.com .

Good luck!
Greg Garrison