Vista driver developers must obtain a Publisher Identity Certificate (PIC) from Microsoft. Microsoft says they won't charge for it, but they require that you have a Class 3 Commercial Software Publisher Certificate from Verisign. This costs $500 per year, and as the name implies, is only available to commercial entities.

Also, drivers must be signed for devices that stream protected content. This includes audio drivers that use Protected User Mode Audio (PUMA) and Protected Audio Path (PAP), and video device drivers that handle protected video path-output protection management (PVP-OPM) commands.