You can develop applications for a custom-designed OS using Microsoft Visual Studio 2008 without installing Platform Builder. To do that, you first obtain an SDK from the developer of the custom-designed OS and install it on your computer.
The creator of the SDK may have included additional files in the SDK to enable you to create a custom standalone virtual CEPC. You can connect a virtual CEPC to Visual Studio to test your applications. For a list of the files, see Windows Embedded Compact 7: Create an SDK for Application Development. For complete directions for creating a virtual CEPC, see Advanced Virtual CEPC.
To learn how to create an SDK for a custom-designed OS, see Windows Embedded Compact 7: Create an SDK for Application Development.