NI does not have a driver and a quick check with Agilent shows that they don't have a driver either.
You can go to http://www.ni.com/devzone/idnet/ and request a driver. You will also find links on how to create your own driver. Your other option is to use the Instrument I/O Assistant.
p.s. In the future, you should use the Instrument control board for posting questions. this board is for NI counter/timer products.
