Windows Web Services Samples
The Windows Web Services API is a native-code implementation of a subset of the SOAP web services support in WCF. This makes Windows Web Services useful when you want to build web services but need to use C or C++ instead of managed code and need to have a minimal set of dependencies.
Many of the people on the Windows Web Services team worked on Indigo before splitting off after our first release. This means that you'll see a lot of similar names and concepts between the two even though their intended users can be quite different.
I've had a few people ask what using Windows Web Services is like and personally I think that looking at examples is a good way to find out. Windows Web Services has an excellent set of samples including a nicely organized index of examples. I'd recommend browsing through the list there starting from the service model examples and then moving to some of the deeper topics.