I have attached a LabVIEW 6i example to this posting that plots arcs in an XYGraph. The main idea behind the VI is using (cos x, sin x) as your coordinates, but it factors in radius and origin. This VI also allows you to account for start and stop angles, although these parameters are limited to a range of -360 to 360.
This program will soon be available in the Example Programs database located at:
http://www.ni.com/support/