Well you both added great info that helped me past that hurtle. so I threw this together.
The TextOut line actually lives in my WM_PAINT message handler not in my WM_MOUSEMOVE. However, "Test" only seems to print in the upper left corner and then that's it.
Now, the reason I'm not trying to print convertedX or convertedY was because I actually did try and it didn't work so I was doing the old "baby steps" thing.
I tried reming out ValidateRect with no change in effect, so I'm stumped. There's only 200 pages left in my 980 page book and I've read EVERY page. I'd expect to be doing better then this..
My only guess is that there is some kind of redraw not happening or being inhibited.