my win32 is very rusty but from what i remember you can't send certain messages willy nilly to windows not created by your application (instance). its somewhat of a security risk if your windows start duking it out.

to get a list of top-level windows you can use the enumwindows function.

that very cool module mentioned earlier looks like your best bet... but you might have trouble on vista. i dont really like the idea of programs messing with explorer myself.