Have you tried the tipp from Peggy, to run the downloader or the install-exe by rightclicking first on those exe-files and choose "..run as administrator..." ?

I'm running a 64bit system Win Vista and now Win 7 since over three years, i've barely never ran into problems with all those programs i run and tested - about 97 % of them working, the rest not working weren't important ones.
And Vue never gave me a problem since then.
I myself started with Vue 5 Esprit at the end of 2005 and since then i've got all the sidegrades up to Vue 8 Infinite.
All installations were working fine, just being asked about the serial key of the version before and then it installed without a problem.

The only problem i ran into about two times while downloading the install files (with different installers, maybe like with Vue 5 and Vue 7), that those download files were corrupted and i had to repeat the downloads. But that could be caused by loosing the i-connection for a moment while downloading.