For whatever reason, Microsoft has decided that driver signing is now REQUIRED in Windows Vista x64 (and I hear this also applied to Windows 2008). There used to be a couple of different ways you could disable this requirement, but as of Vista SP1 neither of these methods work anymore. There are also individual pre-SP1 hotfixes that “fix” Windows so you can’t disable the driver signing requirement. This is a big issue for anyone who wants to use tweaked video drivers, or for anyone who wants to use VMWare Server. Read on for the solution.