AVR-Chat

I am new to this list, and new to the AVR processors, but not new to
imbedded computers.

I will be using an AtMega128 in a project and want to use the SPI to drive a
quad D/A converter (the MAX537) and a couple of DDS chip (the AD9834).  I
want to use PB 6 and 7 to do the selecting of which SPI slave I want to use
by rerouting the SS line to the appropriate slave chip.  I know I can do
this with discrete logic, but does anyone know of a really slick way of
doing this with minimal parts count?  I want to use the two PB lines to be
able to eventually select one of 4 slave chips.

I will be using CVAVR to do the programming.

Thanks for your input.  Any advice will be appreciated.

Steve Jacobson