This link shows all of NIs Analog Out hardware. There are units for PCI, PCMCIA and PXI.
All of these generate a voltage +/- 10VDC and can be easily programmed with any of NIs software packages.
There are also Multifunction DAQ cards that each have 2 analog outputs, digital IO, counter/timers and a variety of analog inputs.
If you hit the MyNI link on the upper left of this page, you should get the name and number of your local NI representitive. They would be the best way to get more details on what you might need.
Ed