Can I run OpenVPN on Windows Vista without turning of the UAC?
Yes you may. Although it is recommended to turn off the UAC on Vista platform, but if you would still lie to prefer running OpenVPN with UAC turned on, you can. It may give you some problem sometimes as Vista sometimes still does not fully give “administrator” privileges to the programs for running even if you tell it to do so. To setup OpenVPN to run with Vista UAC turned on, follow the instructions given here.