The Vista x64 TAP driver signing issue has been resolved, and I was able to successfully install and test OpenVPN on Vista x64 with default driver signature verification in effect.
Change Log: 2007.04.25 -- Version 2.1_rc4 * Worked out remaining issues with TAP driver signing on Vista x64. OpenVPN will now run on Vista x64 with driver signing enforcement enabled. * Fixed 64-bit portability bug in time_string function (Thomas Habets). James
