I did quick MSDN search on 'mciSendString' and at the botttom of it description there's Requirements section:
Windows NT/2000/XP: Included in Windows NT 3.1 and later. Not supported in 64-bit versions.
Windows 95/98/Me: Included in Windows 95 and later.

You can check the rest of functions to make sure that they available on the Windows versions you support.

>Hi all,
>I have to play multimedia files (avi, mpeg, ecc.) on a form.
>I've seen the mci_play.scx under solutions dir and I think I'll can use that example in my app.
>In the form's init event there are some DECLARE statement on WinMM.DLL.
>I would like to know if that DLL is installed by Windows, by the Multimedia Player, Internet Explorer, or whatever else, so I can include the right files in my setup and/or tell my customer the software requirements the PC must have to runs my application.
>thanks
>
>franco