Yes! IconBuilder supports the creation of Windows or .ico files from your Macintosh. Building icons for Windows uses the same procedures as building icons for the Macintosh, although there are some formatting issues you should be mindful of during your initial creation.
IconBuilder comes with a handy PDF guide to help you understand the differences between creating icons for the Mac versus Windows platform.
We've tried to anticipate most questions you might have. However, if you can't find the answer you're looking for here, send us your query and we'll answer it personally.