If you do that you will have no frame rate. You had it right the first time except:
-You must handle WM_PAINT even if you dont actually do anything other than GetDC/ReelaseDC
-You have two LOCAL hdc variables and you assign the hdc is your window proc function so the copy in your Main function is still null when you try to SwapBuffers with it. Declare the hdc as a global (at the top) (this is considered bad practice but for now it will give a quick result.) Then remove the local declarations to it.
-Also I could not get your message pump to work so I replaced it with one along the lines as the FM above did. Using that one should be just fine.
My bad created a bug whilst fiddling with your code, your pump seems to work ok