For most folks, we recommend using MFC because MFC controls are easy to write. You focus on your control's behavior, not the intricacies of OLE interfaces. And, with the new features of MFC 4.2, you can write controls that perform better and implement the cool new OCX 96 features. (You may want to stick with version 4.1 though; since the MFC 4.1 DLLs ship with Internet Explorer, all Internet Explorer 3.0 users will already have these DLLs properly installed on their system.)

But every silver lining has its cloud¡ªand there are two big MFC clouds.

The first is that MFC controls, while not huge, are not tiny. If you're developing controls that don't need the full functionality of an OLE control, you might want to check out other options¡ªperhaps after prototyping in MFC. Gary Winnick

The second cloud is bigger and darker, but might not be in your sky. To run an ActiveX control written with MFC, the correct version of the MFC and C Runtime DLLs must be installed on the user's system. These DLLs are over a megabyte total¡ªquite large to be downloading at 14.4Kbps! The good news is that Internet Explorer 3.0 ships with version 4.1 of the MFC DLLs, so most users will have them installed already. Even if you use the 4.1 DLLs, be prepared to provide and install the DLLs for users running your control in clients other than Microsoft Internet Explorer. Also, you'll have to provide the MFC 4.2 DLLs to all users if you need MFC 4.2 features in your control.