So I got one of those annoying "you really should update to our latest point release that has nothing for you, but we'll bug you about it anyways" messages from vmware server. I'm about to build a new VM, so I might as well be up to date first, and go ahead and download. The installer does it's uninstall and required reboot, and upon login, begins the install process.

This fails not too far in with:

Could not create directory C:\Program Files\Vmware\Vmware VmPerl Scripting API\perl5 (5)

More unable to create errs follow, I cancel, restart the installer with "run as administrator", and now things are installing happily. I suspect the run-as wasn't required, just a new chance to approve the installer after the reboot. stupid vista 'security' feature strikes again.