Microsoft Licensing

I have recently have taken over the IT department from an outsourced IT Company. The Licening is not documented and is a mess.

Is there books or Certifications or some where that will help me understand all of the latest Microsoft Licensing Options geared toward getting Windows 7.

Licensing and Compliance is a sore area and I am needing some direction on where to find good information to make appropriate compliant cost effective decisions?

any advise helps