My problem is, when I run the .exe file downloaded from Naviter today it fails after accepting the license agreement with the message '. .. ActiceSync is not installed'.
One of our Vista computers did have Windows Mobile Device Center installed (or at least something under that name). But it showed exactly the same error as yours did (Active Sync not installed).
Copying files did work, you could use Mobile Wizard in SeeYou select the destination folder on the PDA. But when you clicked Next it responded that Active Sync was not installed.
We installed Windows Mobile Device Center on that computer. The one that's offered for download at Microsoft:
http://www.microsoft.com/windowsmobile/devicecenter.mspxSince the installation everything works as advertized.