Oh yeah, and this doesn't do anything:
Code:
dwreturn == mciSendString(szCmdToDo, 0, 0, 0);
== is for equality, = is for assignment. This is an expression, and isn't doing anything with the return value of the function.

I don't really see the point in your second sprintf() function either, you don't seem to be doing anything with that string, but I guess that's just because you didn't post all your code and you're doing something with it elsewhere.