Sorry, but there are no quick fixes, nor are there simple products you can buy. Sound isolation requires construction. If you already have Rod's book, you already have everything you need.
If they're dropping a hundred grand or whatever on a bunch of new computers, and tearing down walls anyway, but are unwilling to spend the extra few percent to make double walls, they seriously need to reassess their priorities. I suggest you ask them if they're willing to move their own offices into the adjacent rooms.