Windows 7 Sensors and Location
Step 1 install SDK
Wikipedia take on the Windows SDK
SDK version 7, for .Net 3.5 SP1
SDK version 7.1, for .Net 4.0
I have to use .Net 3.5 because I am building an ESRI ArcGIS Engine 10.0 application. Your needs might be different.
Write some code. See the samples. Note they are for C++. See the other samples.