i found this old reference by Paul Kuliniewicz that goes back to win32s/win95/win98/NT
it is handy for seeing what functions are supported on older OS's, and to what degree...
http://vbonline.8m.com/oldapi/ref/index.html
if you poke around his site a bit, he also presents some interesting algorithms
he has more modern sites, blogs, etc, as well