Hi Chris,
The following web site
http://www.maxim-ic.com/appnotes....1138/ln/en
shows how to do the job the right way. It has everything
and more of what you need to do the job.
Practical Data Acquisition using a Windows1-based Power Meter
This application note describes the design of a
PC-based, 14-bit data acquisition system. It takes a
system approach, includes all the necessary building
blocks: analog, digital, hardware, and software. It
discusses each step, testing systems separately before
integrating them, and detailing pitfalls learned along
the way.
Good luck,
Charles Bannister