Let me just confirm my understanding of this feature...
If I do not check the 'require elevation' box, the install will run with the highest available privileges - which will mean the user gets prompted for elevation as it is an installer. It will then attempt to run with whatever they have, and if UAC is disabled will run and maybe work.
If I do tick the box (having appropriately changed the MSI script so it only fires on Vista), the installer will REQUIRE UAC and Admin elevation to proceed.
Right? So if I don't care whether they have UAC or the ability to elevate to God status (assuming their profile allows installation anyway), then I should just not tick the box. If they are admins they can install anway if admin level rights are needed, otherwise the install will fail, and they can call IT Support.
Right?

