Dual Driver,
We use X-plane
http://www.x-plane.com with this
control unit
The software is great - more accurate to fly than any others i have come across, and with the virtual helicopter controls it is very realisic. Only thing missing really is the peripheral view and the motion, but I really think it has helped with both mine and my husband's training, particuarly the hovering!
The unit cost us about £600. It works on Mac and PC and in my opinion it was a valuable investment - not to mention the fun we have when our pilot friends come over and attempt to fly it!
Hope this helps,
WGS