DAC circuit and ampli op
I've used the National TLC7528 DAC recently using the Voltage mode (see page 14 of the data sheet).  Use your 5V supply for the reference which will be the voltage output terminal.  The voltage reference terminal will be your analog output.  This all sounds backwards but it works well.  No need for an additional op amp because it doesn't need any feedback.  On pin 6 you can choose which DAC you want to use (A or B that it's capable of).  Tie pins 1,5, and 6 to GND.  It will stay in write mode, no hassles!